Below board replaces 2364 (8k) with a 28c256 (32k 4 roms) socket.
My design in Kicad
The rom can be selected using the pressing restore while starting the C64. ( This button press to select is not my idea but I liked it, when I find the original idea I’ll post it.
After ordering and testing, I’ll attach the Gerber files.
I’ve got some micro cassettes with programs for P2000 and the Microtrainer (SDK-85).
Lets try to get this into executable code again.
(I sold my Philips P2000 last year before I found these tapes)
I bought a Cassette player (voice memo recorder) from Marktplaats (dutch ebay), and a mini jack cable (2.5mm to 3.5mm)
There are two things i’m going to try.
Converting the recorded audio into executable code using python or Puredata.
And making a print to connect the tape player to the SDK-85.
Connecting the player to a soundcard gave me:
Signed 16bit 44.1 kHz
(there are simular projects like this for C64 tapes and alike)
So there will be FFT tricks involved.
While browsing though this book:
I found this schematic: (page A1-39)
So that’s next to build
My BBC Acorn model B is working again. The original monitor is still dead.
Time to play with some machine code and ROMs.
My machine has a NFS rom installed. (NetFS)
Econet was Acorn Computers’s low-cost local area network system, intended for use by schools and small businesses. It was widely used in those areas, and was supported by a large number of different computer and server systems produced both by Acorn and by other companies.
I found a ROM online called Gremlin. It is a 16K rom file. But at the moment I only got some 28C64 (8k) or 28C256 (32k) eeproms.
32k it is. But de beeb having address line A14 floating high, I need to flash the upper 16k of the 32k ROM.
So I made the 16K rom into a 32K using cat
cp Gremlin\ v1.21\ \(1983\)\(Computer\ Concepts\).rom 16k.rom cat Gremlin\ v1.21\ \(1983\)\(Computer\ Concepts\).rom >> 16k.rom minipro -w 16k.rom -p AT28C256
I got the rom from this page:
https://acorn.huininga.nl/pub/unsorted/roms/Gremlin%20v1.21%20(1983)(Computer%20Concepts).rom
Below booting straight into the monitor program.
Manual:
Ben posted a youtube about Wozmon running on his 6502.
In 1976, Steve Wozniac wrote what’s commonly known simply as Wozmon.
Wozmon is a machine-code monitor program written by Wozniak for the Apple 1. In Only 256 bytes ! Being pure 6502 code easily adaptable.
A monitor program allows you to view/edit and run machine code using simple commands.
I’ve got a different setup as Ben’s computer.
But changing the necessary, and it will run on my 6502.
I’m not using rs232 voltage levels (-7 till -25 and +7 till +25 volts).
I’m using a usb serial uart standard 5v leveling stick …
For address decoder see other post
Compiling the Wosmon gave me an error, DEC is not a valid opcode for a bare 6502 .. but we have a 65c02.
Solution: Add -c02 extra opcodes
error 1 in line 187 of "wozmon.s": illegal operand types > DEC ; Decrement A. # fix .. add -c02 vasm6502_oldstyle -c02 -Fbin -dotdir wozmon.s
Below Apple I Manual with the sourcecode for Wozmon
The board seems to be a X Golden Board, except for the missing logo on the motherboard.
Downloaded pcxtbios and compiled the eproms native in linux. So i don´t have to use dosbox any more.
https://github.com/virtualxt/pcxtbios
cd pcxtbios edit make_linux.sh if needed ./make_linux.sh and you should end up with eproms/27512/basicfc.rom eproms/27512/basicf8.rom eproms/27512/basicf6.rom eproms/27512/pcxtbios.rom eproms/27512/basicfa.rom eproms/27128/basicfc.rom eproms/27128/basicf8.rom eproms/27128/basicf6.rom eproms/27128/pcxtbios.rom eproms/27128/basicfa.rom eproms/27256/basicfc.rom eproms/27256/basicf8.rom eproms/27256/basicf6.rom eproms/27256/pcxtbios.rom eproms/27256/basicfa.rom eproms/ibmxt/u18.rom eproms/ibmxt/u19.rom eproms/2764/basicfc.rom eproms/2764/basicf8.rom eproms/2764/basicf6.rom eproms/2764/pcxtbios.rom eproms/2764/basicfa.rom
I didn’t have enough 28C64, but the 28C256 has the same pinout. It just lacks A14 and A13
So I flashed the compiled ROMs for basic to different Eeproms
minipro -w ./2764/basicfc.rom -p AT28C64 minipro -w ./2764/basicf6.rom -p AT28C64 minipro -w ./27256/basicfa.rom -p AT28C256 minipro -w ./27256/basicf8.rom -p AT28C256
These roms need to be placed in sockets ROM6,5,4,3
| ROM7 (BIOS) | fe00:0-ffff:ffff |
| ROM6 Basic | fc00:0000-fdff:ffff |
| ROM5 Basic | fa00:0000-fbff:ffff |
| ROM4 Basic | f800:0000-f9ff:ffff |
| ROM3 Basic | f600:0000-f7ff:ffff |
Machine Code monitor/editor
I tried to find a machine code monitor for 8088 rom, but did not have any luck there.
I tried mumon88, but that didn´t work.
PCem (short for PC Emulator) is an IBM PC emulator for Windows and Linux that specializes in running old operating systems and software that are designed for IBM PC compatibles. Originally developed as an IBM PC XT emulator, it later added support for other IBM PC compatible computers as well.
The big difference with PCem and Dosbox is the fact that you can configure many systems from 8088 to pentium, soundcards and graphic cards (like hercules, CGA, EGA VGA and alike)
You won’t start in MS-DOS, you can boot from a virtual floppy, just what i needed!
Update : Typing boot disk.img in dosbox works
I’ve installed PCem using:
cd pcem/ sudo apt-get install libsdl2-dev sudo apt-get install libopenal-dev tar xzvf ../PCemV17Linux.tar.gz ./configure make clean make # first start (complains about roms, but creates ~/.pcem/... ./pcem cd ~/.pcem/roms # git clone roms git clone https://github.com/BaRRaKudaRain/PCem-ROMs.git mv PCem-ROMs/* ./ rm -rf PCem-ROMs
Below a simple example, booting a floppy with a custom made bootsector.
I’m still searching for our bootblock demo, which uses VGA graphics and a music loader using Soundblaster.
We made this around the 90’s, and i have never seen a demo then booting a demo without dos.
Scrollers, music, starfields etc.
NOTE: Dos calls can’t be used, that’s not loaded. So NO int 21h software functions!
The disk image I created using my real original 5.25″ floppy, and converted this with my Fluxengine.
One of the other bootblock thingy’s I made, An amiga guru meditation error. (below a old capture)
When a corrupted disk or faulty software was booted using a amiga you often could see an error like this, now you could have it on you PC!
Original screen capture of a Guru Meditation.
You can see, mine is a little different, because of the font spacing and color.
PCem info
Systems / motherboards emulated :
8088
AMI XT clone
Atari PC3
Compaq Portable Plus
DTK Clone XT
(c)Anonymous Generic Turbo XT BIOS
IBM PC
IBM PCjr
IBM XT
Juko XT clone
NCR PC4i
Phoenix XT clone
Schneider Euro PC
Tandy 1000
Tandy 1000HX
Thomson TO16 PC
Toshiba T1000
VTech Laser Turbo XT
Zenith Data SupersPort
Xi8088
8086
Amstrad PC1512
Amstrad PC1640
Amstrad PC2086
Amstrad PC3086
Amstrad PC5086
Amstrad PPC512/640
Compaq Deskpro
Olivetti M24
Sinclair PC200/Amstrad PC20
Tandy 1000SL/2
Toshiba T1200
VTech Laser XT3
286
AMI 286 clone
Award 286 clone
Bull Micral 45
Commodore PC30-III
Compaq Portable II
Dell System 200
Epson PC AX
Epson PC AX2e
GW-286CT GEAR
IBM AT
IBM PS/1 Model 2011
IBM PS/2 Model 30-286
IBM PS/2 Model 50
IBM XT Model 286
Samsung SPC-4200P
Samsung SPC-4216P
Toshiba T3100e
Tulip AT Compact
386SX
Acermate 386SX/25N
AMI 386SX clone
Amstrad MegaPC
DTK 386SX clone
Epson PC AX3
IBM PS/1 Model 2121
IBM PS/2 Model 55SX
KMX-C-02
Packard Bell Legend 300SX
Samsung SPC-6033P
386DX
AMI 386DX clone
Compaq Deskpro 386
IBM PS/2 Model 70 (type 3)
IBM PS/2 Model 80
MR 386DX clone
Samsung SPC-6000A
486
AMI 486 clone
AMI WinBIOS 486 clone
Award SiS 496/497
Elonex PC-425X
IBM PS/2 Model 70 (type 4)
Packard Bell PB410A
Socket 4/5/7 (Pentium)
ASUS P/I-P55TVP4
ASUS P/I-P55T2P4
Award 430VX PCI
Epox P55-VA
Intel Advanced/EV (Endeavor)
Intel Advanced/ZP (Zappa)
Intel Premiere/PCI (Batman's Revenge)
Packard Bell PB520R (Robin LC)
Packard Bell PB570 (Hillary)
Super Socket 7 (K6-2/III)
FIC VA-503+
Socket 8 (Pentium Pro)
Intel VS440FX
Slot 1 (Pentium II)
Gigabyte GA-686BX
Graphics cards emulated :
3DFX Voodoo Graphics
3DFX Voodoo 2
ATI Graphics Pro Turbo (Mach64 GX)
ATI Video Xpression (Mach64 VT2)
ATI VGA Edge-16 (ATI-18800)
ATI VGA Charger (ATI-28800)
CGA
Cirrus Logic CL-GD5429
Cirrus Logic CL-GD5430
Cirrus Logic CL-GD5434
Compaq CGA
Diamond Stealth 32 (Tseng ET4000/w32p)
Diamond Stealth 3D 2000 (S3 ViRGE/325)
Hercules
Hercules InColor
IBM EGA
IBM VGA
MDA
MDSI Genius
Number Nine 9FX (S3 Trio64)
OAK OTI-037
OAK OTI-067
Olivetti GO481 (Paradise PVGA1A)
Paradise Bahamas 64 (S3 Vision864)
Phoenix S3 Trio32
Phoenix S3 Trio64
Plantronics ColorPlus
S3 ViRGE/DX
Sigma Color 400
Trident TVGA8900D
Trident TGUI9400CXi
Trident TGUI9440
Trigem Korean VGA (Tseng ET4000AX)
Tseng ET4000AX
Wsye 700
Sound cards emulated :
AdLib
AdLib Gold
Ensoniq AudioPCI
GameBlaster
Gravis UltraSound
Sound Blaster v1.0
Sound Blaster v1.5
Sound Blaster MCV
Sound Blaster v2.0
Sound Blaster Pro v1
Sound Blaster Pro v2
Sound Blaster Pro MCV
Sound Blaster 16
Sound Blaster AWE32
Sound Blaster PCI128
Windows Sound System
When selling a large part of my computer collection I kept a few odd pieces.
Amongst those was a 8088 DIY machine.
It is a 50PTX3 motherboard with a 8088 compatible CPU
Tested the power adapter first, a nice 5V and 12V.
Then I plugged the power in the Motherboard add plugged a test ISA card in the slot.
After turning the machine on I saw the Address leds flashing
A NEC D70108C from 1984, which is 8088 pin compatible with Intel 8088 but faster, and has some extra functionality.
The empty socket is for the 8087 Co-processor.
Everything pretty dirty
Adding an 8bit Isa hercules/CGA card.
It starts! .. But there is no Floppy controller (yet)
I’ve dumped the Bios to a file and used a hexeditor to play around.
So that’s why there is a bad checksum.
Installing a ZIF socket (Zero Insertion Force) to make things easier to modify.
Burned GlaBios on the Eprom and now I can continue to play around.
So why? Why this all ..
I want to play around with old 8088 assembly code again, but not as I did before using a Dos machine, but hardcoded into Eproms.
I’ve got 8 banks for ROMs and the source code for GlaBios is available.
In the past Edk and me wrote a boot demo, so it was not utilizing Ms-Dos functions. Maybe i can get some graphical and sound stuff working straight from the Bios.
Some commands:
# Dump the bios to file minipro -w original.rom -p AT2764A@DIP28 xxd and hexdump to view the dump I've used ghex to alter the ROM # Write a new bios to a 28C64 (same Eeprom i've used for the C64 Cartridges) minipro -w /home/henri/Downloads/MYROM -p AT28C64
GlaBios source code:
https://github.com/640-KB/GLaBIOS/blob/main/src/GLABIOS.ASM
I was planning to disassemble the Phoenix Bios, but it’s quite hard to differentiate between code and data, there are no named pointers and you have to interpret every line of code.
So GlaBios it is ..
First code to look at:
This is after the whole post reset. There is a reset pointer at ffff:fffe Which points to the bootstrap routine, which ends in below machine code. I'm going to plug my own code over here. (See the funny remark about Monster as being displayed in one of above pictures) ;----------------------------------------------------------------------------; ; INT 18 - Unbootable IPL ;----------------------------------------------------------------------------; ; Display a disk boot failure message and wait for a key to cold reboot. ; ; This may be re-vectored to ROM BASIC, if present. ; ; Size: 18 bytes ;----------------------------------------------------------------------------; INT_18 PROC ASSUME DS:_BDA_ABS PRINT_SZ BOOT_FAIL ; print boot failure string XOR AX, AX ; AH = 0 (wait for key) MOV DS, AX ; DS = 0000 MOV WARM_FLAG_ABS, AX ; do a cold boot INT 16H ; wait for key press JMP BOOT ; reboot INT_18 ENDP BOOT ENDP ;----------------------------------------------------------------------------; ; ; END OF BIOS POST/BOOTSTRAP ; ;----------------------------------------------------------------------------; ASSUME DS:_BDA STRINGS PROC ;----------------------------------------------------------------------------; ; Banner Strings ; BANNER_STRINGS PROC IF POST_GLADOS EQ 1 BOOT_BEGIN DB CR, LF DB 'Starting GLaDOS...' NL2_Z DB LF ; two NL's, null term'd ENDIF NL_Z DB CR, LF, 0 ; one NL, null term'd BOOT_FAIL DB 'Disk Boot Fail.' DB ' You monster.' NL2_ANY_KEY DB LF NL_ANY_KEY DB CR, LF ANY_KEY DB 'Press the Any Key' DB '...'
Assembly stuff
I’ve got Dosbox installed on my machine.
git clone https://github.com/640-KB/GLaBIOS.git
I copied MASM.EXE and LINK.EXE in the GLaBios src directory.
edit make.bat
change
MASM GLABIOS;
into
MASM /DVER_DATE=”05/24/23″ /DARCH_TYPE=”T” /DCPU_TYPE=”V” GLABIOS;
start dosbox
mount c: /home/henri/projects/
c:
cd glabios/src
make.bat
Started drawing a Cassette interface in Kicad.
This so i can read back my old cassettes with programs.
(And write some new stuff)
I’m planning to buy a small micro cassette player.
With schematic below, I’m going to use it as save/load device.
But also with the same player, I’m going to convert the tape to a wave file, and try to decode the program using python.
While I’m at it, reading the old manuals, a RS-232 interface would be nice also!
UPDATE 20231016
This is the final version
Information about the 7655A.
A eprom WITH IO ports! Amazing piece of history hardware.
Testing some sims on Linux and Android
JiffyDOS is an enhanced DOS for the C64. The software is programmed onto ROM chips that replace the Kernal ROM chip on the motherboard and the DOS ROM chip in the disk drive. JiffyDOS is intended to provide greater speed, commands and convenience than on stock systems.
The 1541 drive is a computer on its own, using a 6502 and VIA chips.
(See other pages) (C64 uses a 6510, that is the same slightly modified version of the 6502)
A cool example of the drive being an OS/computer on its own:
https://www.youtube.com/watch?v=zprSxCMlECA
Some notes:
Did I misspell kernel? NO
(Below from Wikipedia)
The KERNAL was known as kernel inside of Commodore since the PET days, but in 1980 Robert Russell misspelled the word as kernal in his notebooks. When Commodore technical writers Neil Harris and Andy Finkel collected Russell’s notes and used them as the basis for the VIC-20 programmer’s manual, the misspelling followed them along and stuck.
Original Kernal: 901227-03
8-kilobyte 2364 ROM 4K * 8 bits PROM
28C265 = 32K * 8bits
Romselect should be /(a15 * a14 * a13) depending on ram/rom switch.
| SEL0 | SEL1 | |
| 0 | 0 | rom0 |
| 0 | 1 | rom1 |
| 1 | 0 | rom2 |
| 1 | 1 | rom3 |
$E000-$FFFF – ROM
57344-65535
KERNAL ROM or RAM area (8192 bytes); depends on the value of bits #0-#2 of the processor port at memory address $0001
$FFFA-$FFFF – hardware vectors
%x0x: RAM area. %x1x: KERNAL ROM.
So i made a nice display case for this SDK.
I made some designs and came up with this:
I just took a 12mm x 60mm piece of wood, and made a slit for the acrylic plastic using a circular saw, and removed a part for the back-plate using a wood router. I found a piece of acrylic in my shed, cut it to the right size using the circular saw. Slapped some paint on the wood.
I want to be able to use the sdk whenever i want, so i made a sliding window thingy. ( With wooden handle so the frame looks intact when closed. )
Then I 3D printed some holders, which I designed using Openscad.
Openscad code
difference(){
difference(){
translate([0,8,1])
cube([20,15,10],center=true);
union(){
cylinder(h=9, d1=9, d2=9, center=true);
translate([0,0,3])
cylinder(h=9, d1=15, d2=15, center=true);
}
}
$fn=100;
translate([0,12,0])
cylinder(h=30, d1=3.5, d2=3.5, center=true);
}
I will probably add a powerconnector and lasercut a hole for the keypad at a later stage.