64 MB Hard Disk for your Adam!

I have been experimenting with MicroFox’s Floppy Disk Emulator, also known as the Virtual Disk Drive (VDD). Using some software I wrote on my PC I was able to create a 64mb disk image that the VDD would open (64mb is the limit it appears) and then initialize it with EOS and it is recognized as a 64MB disk. The AdamEM emulator on the other hand doesn’t like it, but that is ok.

Here is a copy of this blank, initialized disk image. Copy some files to it, let me know how it works out.


Type In – A DDP Verifier

In the late 70’s, early 80’s there were many magazines and books devoted to the personal computers of the time that contained programs that you could type into your computer, save and use. Though tedious it was often the only way many people could get new software for their orphaned systems. With this in mind I present DDP Verify, a small type in that will let you non-destructively verify if your tapes are good or not.

Let’s Make a Tape – Squashing a Bug

To begin with you will need a blank tape and a tape containing a copy of Smart Basic. The reason for two tapes is we will be creating a quick booting tape that will be used to verify other tapes. If you happen to run any of the programs with the Smart Basic tape in drive 1 IT WILL ERASE you Smart Basic tape. If you have an original Colecovision Smart Basic version 1.0 you will want to do something before you get started. You will want to squash a bug!

There is a bug in Smart Basic in that every time you load a program with a REM or DATA statement it will add an extra space after the REM or DATA, eventually pushing your code off the line and ruining the code. To fix this is easy:

  1. Start Smart Basic
  2. Type the following code:10 PRINT “Data bump bug fix”
    20 POKE 15830,8
    30 POKE 15831,55
    40 POKE 15832,19
    50 POKE 15824,216
    60 NEW
  3. Save the code as HELLO on the tape using save HELLO (it is case sensitive)
  4. Reboot your tape and it should tell you the data bug is fixed, if not then you saved it with the wrong name

If you already have a HELLO program on your tape, load it and add the code above to it in the beginning. You can eliminate line 10 and line 60 if you want and combine all the POKEs onto one line.

Typing in the Program

Now we are ready to start typing in earnest! To create the DDP Verify tape we need to type in the loader which reads the data and the data statements which holds the program. First I will explain the loader:


1 HIMEM :39000: R = 40004: B = 40128
2 DATA 1,0,0,17,0,0,62,8,33,192,156,205,246,252,201
3 FOR K = 40000 TO 40014: READ D: POKE K,D: NEXT K
6 IF A = -3 THEN CALL 40000: PRINT " DONE":END
8 IF A = -1 THEN READ A: FOR K = 0 TO 15: POKE B,A: B = B + 1: NEXT K: GOTO 5
9 POKE B,A: B = B + 1: GOTO 5

How it works:

1 > Tell SB to not touch memory above 39000 and set up the variables R and B. R holds where we will poke tape records and B is where our tape record buffer is.

2 > This is a small machine language (ML) code that we use to access the EOS routines to write a block to tape. The variable R which we defined in line 1 points to the block low byte. Here is the code:

LD BC,0 ;Block High Byte
LD DE,0 ;Block Low Byte
LD A,8 ;Tape drive 1
LD HL,40128 ;Buffer
CALL 0FCF6h ;Write one block

3 > This line reads in the ML in line 2 and pokes it into memory starting at address 40128 which we defined on line 1

4 > This line pauses and prompts you to put in the blank tape we will be turning into a the Verify tape – PLEASE follow this instruction.

5 > This reads in a byte from the data statements. The byte can have one of 4 values:

0 – 255 = This is a byte that will be poked into memory
-1 = This tells the loader that the next byte to be read gets poked into memory 16 times – This saves on typing
-2 = This tells the loader that the next byte contains the record number this block of data gets saved to
-3 = This tells the loader we are done, write the block to tape and end

6 – 8 > These lines process the data that is read as described above

9 > Pokes the data into memory at B, increments B and then loops back to line 5 to do more

Once you have typed in the LOADER program save it. Now we will type in the code:

DDP Verify

30 DATA -2,0
31 DATA 243,049,142,211,120,050,255,255,033,050,201,017,088,246,001,003
32 DATA 000,237,176,001,000,000,205,032,253,001,192,001,205,032,253,033
33 DATA 000,000,062,003,205,041,253,033,000,008,062,002,205,041,253,205
34 DATA 056,253,017,000,004,033,000,000,001,128,000,205,023,253,033,192
35 DATA 011,062,004,205,041,253,033,000,056,062,001,205,041,253,033,128
36 DATA 056,175,205,041,253,001,001,007,205,032,253,014,003,006,001,022
37 DATA 000,030,000,033,192,011,025,017,032,000,121,203,007,203,007,203
38 DATA 007,203,007,128,205,038,253,006,031,014,023,022,000,030,000,033
39 DATA 000,008,205,054,252,062,032,017,000,003,033,000,008,205,038,253
40 DATA 062,000,050,053,201,033,054,201,205,041,201,033,187,201,205,013
41 DATA 201,205,108,252,033,005,202,205,013,201,062,028,022,000,030,006
42 DATA 205,057,252,006,255,014,001,017,000,000,197,033,184,201,205,041
43 DATA 201,001,000,000,058,255,255,033,000,001,205,243,252,032,004,062
44 DATA 079,024,020,033,110,202,205,013,201,205,108,252,033,005,202,205
45 DATA 013,201,062,127,050,053,201,205,051,252,193,019,016,204,062,001
46 DATA 185,032,006,014,000,006,001,024,193,033,007,202,058,053,201,183
47 DATA 040,003,033,059,202,205,013,201,205,108,252,024,131,058,166,254
48 DATA 087,058,165,254,095,213,062,028,022,000,030,020,205,057,252,205
49 DATA 041,201,209,062,028,205,057,252,201,126,183,200,205,057,252,035
50 DATA 024,247,000,000,000,000,012,043,045,045,045,045,045,045,045,045
51 DATA 045,045,045,045,045,045,045,045,045,045,045,045,045,045,045,045
52 DATA 045,045,045,045,045,045,043,124,032,068,068,080,032,086,101,114
53 DATA 105,102,121,032,040,099,041,032,087,105,108,108,105,097,109,032
54 DATA 072,105,099,107,115,032,124,043,045,045,045,045,045,045,045,045
55 DATA 045,045,045,045,045,045,045,045,045,045,045,045,045,045,045,045
56 DATA 045,045,045,045,045,045,043,013,010,032,111,032,061,032,082,101
57 DATA 097,100,105,110,103,032,079,032,061,032,080,097,115,115,032,127
58 DATA 032,061,032,070,097,105,108,000,111,008,000,032,082,101,112,108
59 DATA 097,099,101,032,116,097,112,101,032,119,105,116,104,032,116,104
60 DATA 101,032,116,097,112,101,013,010,032,116,111,032,098,101,032,118
61 DATA 101,114,105,102,105,101,100,032,097,110,100,032,116,104,101,110
62 DATA 013,010,032,112,114,101,115,115,032,097,110,121,032,107,101,121
63 DATA 046,046,046,032,000,024,000,032,078,111,032,101,114,114,111,114
64 DATA 115,032,112,114,101,115,101,110,116,044,032,112,114,101,115,115
65 DATA 032,097,110,121,013,010,032,107,101,121,032,116,111,032,099,111
66 DATA 110,116,105,110,117,101,046,046,046,032,000,032,069,114,114,111
67 DATA 114,040,115,041,032,112,114,101,115,101,110,116,044,032,112,114
68 DATA 101,115,115,032,097,110,121,013,010,032,107,101,121,032,116,111
69 DATA 032,099,111,110,116,105,110,117,101,046,046,046,032,000,032,065
70 DATA 100,106,117,115,116,032,116,097,112,101,032,116,104,101,110,032
71 DATA 112,114,101,115,115,013,010,032,097,110,121,032,107,101,121,032
72 DATA 116,111,032,099,111,110,116,105,110,117,101,046,046,046,032,000
73 DATA -3

This is the code for DDP – Verify. Once you have typed in it save it as VERIFY. DO NOT RUN IT – If you do it will ruin the tape you have in the drive.

After saving VERIFY remove the SMART BASIC tape and put in the blank INITIALIZED one you made. Run VERIFY and follow the prompts. When done you should be able to reset the system and DDP Verify will start. You can then follow the prompts on the screen to start verifying your tapes.

The Screen

When DDP Verify is running it will show a ‘o’ as it is reading a block, and a ‘O’ if the block passes or the checkerboard if it doesn’t. If you want to know which block it is you can  count them on the screen. Each line is 32 blocks long so if you fail on the first column on row 3 then you failed on 2 * 32 + 1 or block 65. I kept things simple to decrease the amount of code and typing in.


If you decide to do this let me know.


  • Disk & Tape images to use in an emulator and the DDP Verify basic code VERIFY.ZIP

Formatting a Disk (help needed)

I do not have an actual disk drive to test this on, I use the emulator of the floppy emulator on my Adam but if you do can you test this:

  1. Boot up CP/M on floppy
  2. Type Format
  3. When prompted put in a blank disk and format it, verify when done
  4. Boot Smart Basic
  5. Depending on your setup type CATALOG,D1 (or D3 or D5) to view the catalog of the smart basic disk
  6. Now remove the Smart Basic disk and insert the CP/M formatted disk
  7. Type INIT HELLO,D1 (or D3 or D5, again varies based on setup)
  8. Now type 10 PRINT “HELLO WORLD”
  9. Save this with SAVE WORLD
  10. Reboot with the Smart Basic disk
  11. Put the disk that was formatted with CP/M in and type LOAD WORLD
  12. Did it work?

Make Your Own 5 Minute Data Pack

This is a very brief post that I will give more information on later:

As part of the first of many new games that I will be selling for the Adam this year I have come up with a way of creating quick data packs to hold these games. My games (and other software) are standalone products and as such do not need a complete 256kb data pack to hold them. So to make it easier I have figured out how to make a data pack in 5 minutes that will hold about 20kb of data. To do this is easy, but before you do you may wish to read this post on making a true data pack as you will be doing the same thing with some minor changes.

What you need:

  • An original super game pack, buck rogers, donkey kong junior,  or the like. It can not be a normal data pack
  • a new blank audio tape – any size is ok
  • a compatible tape deck
  • a copy of file manager

Making a new tape:

To make a 5 minute tape you are going to do what is detailed in the post about making data packs from audio tapes with the exception that you will need a timer. Set the timer for 5 minutes then start recording side A. When the time goes off. stop both decks, flip both tapes and record side B. Then follow the steps in the previous post about making the holes in the new tape.

Putting software on the new tape:

You can use File Manager to copy up to 23 blocks on the new tape you created. The first block is the code that loads when you reset the Adam and needs to be on block 0. The remaining blocks hold code that you would load with a loader routine that is part of the block 0 code. I will detail how this can be done later.

Debug.Asm – Z80 Development Tool

If you are going to be doing any serious z80 programming then you will quickly find a need for this program. It is code that you can include at the end of your z80 source code and then call it with a simple JP CodeDump command. When you do this it will show you the values of all the registers when it was called and let you move around memory starting at the value you put in the source code at CD_CurLoc.  The only caveat is that you need to be in 32 column mode when you enter it. Any other mode will be hard if not impossible to read.


Hello World – Z80 development

(I want to apologize in advance, I am not a fantastic writer)

I like to code in machine language. Using ML you have (almost) complete control over the Adam and can make it do things as fast as it is possible for it to do it.

Writing ML code on the actual Adam for me is hard because I have been been using modern computers for so long I am used to being able to cut and paste, have multiple files, compile fast etc.  So I like to create my code in Windows, compile it and then transfer it to a disk image for testing in the AdamEM emulator and if I want moving it to the real hardware.

Doing so has involved using my editor of choice (ConTEXT), and then using DosBox to emulate a DOS machine and compiling the code using the TeleMark cross-assembler. On a 32 bit machine I could have eliminated DosBox and just used the Command prompt in Windows, but with a 64 bit machine DosBox is required because TeleMark is a 16 bit program.  Once I compiled the program I would then use various methods to get it into an image, mostly WRDISK and sometimes TDOS if I was programming for a CP/M environment but I always felt these were cumbersome so I have been working on a method of creating a disk (or tape) image of the compiled program I am working on and have it just load when I start the emulator (or real hardware). After disassembling the Smart Basic Loader, studying the EOS programmers Guide and banging my head against the wall with disk interleaving I finally was able to create a “simple” process to take my machine language source code, compile it and create a working disk image using just one command.

Hello World

At some point every programmer has made a “Hello World” program. In Smart Basic this is as simple as:

10 PRINT “Hello World”

Writing one in machine language to use under EOS is a little more convoluted to get started as you have to initialize the Video Display Processor to even see anything. Once you get that setup then you can print to the screen.  (Click here to view the source code).

Compiling the Code

To compile the code use the Assemble batch file. If all goes well and there are no errors you will have a usable disk (and tape) image. If you look at the assemble.bat file you will see how it works:

echo off

rem This batch file will assemble the source code file
rem passed on the command line for example: assemble filename
rem where filename is the name of z80 code you wish to
rem assemble and has the extension of .asm. Do not add an
rem extension. The batch file will use filename for the
rem name of the resulting disk and tape images it creates

rem Did they pass a filename to assemble? If not then exit
if "%1"=="" goto NoFileName

rem Do some clean up of old .obj, .lst, .dsk and .ddp files
if exist %1.obj del %1.obj
if exist %1.lst del %1.lst
if exist %1.dsk del %1.dsk
if exist %1.ddp del %1.ddp

rem Now to assemble the file passed TASM will return an error if
rem we could not assemble it and if that happens we will exit

tasm -80 -b %1.asm
if ERRORLEVEL 1 goto AsmError

rem The code assembled ok so now we need to put it in the disk
rem image for use with the emulator and a real Adam. If you are
rem curious how ImageMkr works just run type imagemkr at the prompt

imagemkr %1.obj %1

rem We are all done so lets exit

goto Exit

echo No file name was passed to assemble
goto Exit

echo Error while assembling
if exist %1.obj del %1.obj
if exist %1.lst del %1.lst
goto Exit

rem All done so exit
echo on


Help – resolved

Can you do the following and let me know your results:

  1. Download this zip file
  2. Unzip it and start AdamEm with File Manager as disk 1 and the image called Heather as disk 2
  3. Press F5 to switch to disk 2, F2 for Media Functions and F4 for edit
  4. Press F3 for Block Number and type in a 2 and hit enter.
  5. Press Enter again
  6. Now you are looking at Block 2 Sector 0. On a real Adam press Home and Up arrow until you are looking at Sector 4. In the emulator press the “5” on the keypad and the up Arrow (at same time)
  7. Does it look like the screen shot to the right? All zeros?
  8. If it doesn’t let me know
  9. If it does then  humor me and go to Hex Edit and upload the file called HEATHER.DSK and then scroll down till you get to the section starting with 00000A00
  10. You will see that there is code there, but the same corresponding bytes in the image are zeros. You can verify this by scrolling up a to sector 3 in the image on the emulator and seeing the last of the code that loads

Please let me know your results – either here or on Facebook


Thanks to the information from Eric I was able to determine that I was not taking into account the interleaving of the data on a disk image. The tape images do not use that so it confused me when I started working with disk images. If you are curious how it works here it is where the first number is a 256 byte sector and the second number is the actual sector it should go in. This is using 4kb blocks:

0 -> 0
1 -> 1
2 -> 10
3 -> 11
4 -> 4
5 -> 5
6 -> 14
7 -> 15
8 -> 8
9 -> 9
10 -> 2
11 -> 3
12 -> 12
13 -> 13
14 -> 6
15 -> 7