Tag Archives: retro

Hercules to VGA

2022-11-16 fash

While playing with MuseScore….
(Typesetting some scores for Pipes and Flute)

This came in: WOOOT

This is a Trident VGA card. While having a 16bit ISA connector, it can work in a 8bits ISA slot.

A while ago i bought a Laser XT/3, that’s the one my parents had.
This is where i did a lot of assembly programming on.
It’s a 8086 cpu, 640K and has a Hercules/CGA graphics card.

I found loads of assembly files and i want to see if i can get it running again.
While some code was written for hercules, ( That’s the monochrome image you see in the example above ) and a few for EGA (4 colors).

Most of it was written for VGA. Probably on a later machine like a 80386?

But i know there are vga cards for 8 bit msdos computers, and i found one. ( This one is even autodetect, so no jumpers to figure out)

So i’ve put this card in the machine, turned it on, and it works!
I’ve got only 2 examples living on the harddisk of the machine, both black and white … 🙂
I have to search for interesting code in hundreds of files.

Some friends of mine, picture was taken from an amiga genlock digitizer

The intro pages of a “amiga emulator” WHERE is the rest??? (end is a cga starfield demo)

Hercules Card

There is not much info available about this card:

Max resolution (Hercules) : 720×348
15 pin analog monitor port (CN1)
BIOS enabled JP1 Pins 1 & 2 closed
BIOS disabled JP1 Pins 2 & 3 closed
CGA selected SW1 On
MDA (Hercules) selected SW1 Off

Floppy drive boot

My friend EDK and I made some demo’s like

Sakura demo

And a boot demo, which was able to start from a bootsector, went into a graphic mode and ran a demo with sound. Edk wrote a sector loader for this.
I have some 5.25 inch floppy disks, labelled boot demo. So i wanted to try this today …
I needed to change the boot order, so i went online to search for jumper settings.

I see a led when it tries to boot, but my disks are probably formatted 720Kb instead of 360Kb, which this drive is.

So …. TODO!

Find a 720Kb floppy drive (5.25 inch), and sort through my code!
There is a 8bit soundblaster compatible soundcard that i bidding on online, hopefully i’ll get it

Assembly and modes

I wasn’t sure how to sort the assembly code into Hercules and VGA compatible, but i used this table (There are also extended modes for higher resolutions)

mode 0x00	text 40×25 gray
mode 0x01	text 40×25 16 colors
mode 0x02	text 80×25
mode 0x03	text 80×25 16 color
mode 0x04	graphics mode (CGA) 320×200
mode 0x05	graphics mode (CGA) 320×200
mode 0x06	graphics mode (CGA) 640×200 (B/W)
mode 0x07	text 80×25 Hercules
mode 0x0F	graphics mode 640×350? gray
mode 0x10	graphics mode 640×350?
mode 0x11	graphics vga 2 colors
mode 0x12	graphics vga 16 colors
mode 0x13	graphics 320×200 256 colors

# Set VGA mode
    mov ax,13h
    int 10h         ;screen 320x200 256 colours

# Exit VGA mode
    mov ax,3
    int 10h         ;screen  80x25 text
    mov ax,4c00h
    int 21h         ;back to DOS

Computer

7 segment displays/keyboard decoders in SDK’s

2022-10-18 fash

There are a lot of old develop boards for all kinds for cpu’s.

These where build to learn machine code programming. Mostly made in the 80’s, and based on populair cpu’s at that time.

I own a some of these SDK’s (System Design Kits)

Most of these use a keyboard scanner which is also connected to 7 segment displays.

The way they work is practically the same. There is a VIA or PIA. Versitile interface adaptor, or Peripheral interface adaptor. These have two times 8 bits to control devices.
When using 4 bits and convert these to 16 lines by using a 75ls145 for example. If you put a counter on those 4 bits, you sequently activate 1 of 16 lines. These lines you can use to scan a keyboard matrix OR display a character on a 7 segment display. These display’s won’t hold the data (and show the character) when not activated. The trick is to update de display fast enough so you don’t see the flickering on/off.

Activate a line and read a byte with the VIA = Reading keyboard row
Activate a line and write a byte with the VIA = Display on a segment

These VIA/PIA’s where made with specific timings to match the CPU.
6522/6820/8255

Below you see some different implementations of these keyboard/display combo’s

Microprofessor MPF-1 kit (ignore red circle)

My version using darlington arrays (ULN2003)

When looking at the 8085 version you see transistors being a ULN2003 is a chip with those transistors/amplification enclosed.
It doesn´t draw much current from the bus, and diodes protect the way the current flows.

Computer

SDK-85 searching archives

2022-09-28 fash

Found these old .. old mini-cassettes .. wish i could read these now.
The sdk units we had, had tapedrives and few other hardware devices you could play with. Like a motor you could control, which had a disc with slots in it on top. These slots could be read and counted with a sensor to determine the speed.

Also this scanned pages, from school i found. There should also be a little notbook with programs and notes ..

Found some ROM files also

Practicum handl digi computertechniek I – oa Microtrainer

Apparently we had something called a bb-board.
These had motors and speakers and such

This part contains the motor with sensor

I want to try to get some parts working by rebuilding. Like the speaker .. because … i found some own written software!

I found als programs written by my friend Martin

Computer

SDK-85 in 2022

2022-09-28 fash

I was posting about the 8085 System Design Kit in may, but now i’ve got one!

8085 Machinecode at school

I found one online, it is a very clean almost like its never been used version!

More follows!

More info at http://www.bitsavers.org/components/intel/8085/

Computer

6502 Update

2022-09-12 fash

New address decoder in place!
Connected RAM/ROM/SID/VIA1/VIA2 and ACIA

ROM	8000-FFFF
SID	7000-700F (sound)
VIA1	6000-60xx (Hex key matrix)
ACIA	6800-68xx (serial)
VIA2	5000-50xx (led test at the moment)
RAM	0000-3FFF

To plan: Bigger maxtrix keyboard and other displays

Got a serial connection working between the 6502 and my linux machine!

At the moment when a reset occurs , hello is being printed.
Text typed in the minicom terminal, is echo-ed back and displayed on the LCD display.

Things learned: Do not trust internet schematics blindly!

The crystal used for the ACIA (pin 6/7 1.8432Mhz needs a 1M ohm resistor parallel over the crystal, and a 30nF capacitor from pin 7 to GND

When using a terminal emulator, and using 3 wires. Disable hardware handshake.

What didn´t work as planned:

New amplifier schematic for the SID. There is too much noise.

Bought a dual power supply (5V and 12V). But this one has a lot of signal noise on the SID part and even my battlestation speakers!

LED test 2nd via

PORTB = $5000 ; VIA PORTB
PORTA = $5001 ; VIA PORTA
DDRB = $5002  ; Data direction register
DDRA = $5003  ; Data direction register

LED  = %10000000

	.org $8000

reset:

	lda #%11100000 ; Set top 3 pins on port A to output
	sta DDRA

	lda LED 
	sta PORTA

loop:		; done loop until doomsday
	jmp loop

irq:
nmi:
	.org $fffa
	.word nmi
	.word reset
	.word irq

ACIA part

ACIA_RX = $6800
ACIA_TX = $6800
ACIA_STATUS = $6801
ACIA_COMMAND = $6802
ACIA_CONTROL = $6803

    lda #$00
    sta ACIA_STATUS
    lda #$0b
    sta ACIA_COMMAND
    lda #$1f
    sta ACIA_CONTROL

Computer

Cool terminal combo

2022-09-07 fash

I was using zevv’s bucklespring way back since he was beta testing.
https://github.com/zevv/bucklespring

Also cool-retro-term, i used whenever i felt nostalgic.

But both at the same time, how much fun is that!

(Both newly installed on my laptop, which i had to reinstall, because i f*cked it up beyond repair. installing openxr stuff. OpenXR is an open, royalty-free standard for access to virtual reality and augmented reality platforms and devices. )

Computer

Eurocards

2022-09-03 fash

UPDATE 20240927 PCBs are in

I found some stuff while sorting out some old computer stuff.
Way back, when my Amiga was my main computer, i wanted to make my own version. A modular one.

So i started to segmentize the amiga, to put it on several exchangeable cards.

Eurocards are standardized prints 150mm x 100mm, mostly with a DIN41612 connector.

When you make modules you can change/upgrade/test, you can have a very easy interchangeable system using a backplane like this

So i started planning those modules:

CPU – 68000 but upgradeable to 68030 or alike
Memory – With expansion
Sound
Video
More IO possibilities
Keyboard (see more at the bottom of this page)

I had a nice case which could hold a big backplane, custom powersupply. And a front panel containing drives, leds and knobs. (I know i have more info on this somewhere on my fileserver)

A nice example picture i found on danceswithferrets website

I never finished this project.
I used Tech Manuals and print layouts to understand how things where done.

I started to draw the modules like they where placed on the print on semi transparent (chalk)paper, the kind of paper that was used for electronic and mechanic diagrams.

UPDATE 20240927 PCBs are in

Computer

Selling a lot of my computer collection

2022-09-02 fash

UPDATE : Bought after selling these

The last days i’ve been selling a lot of my old computers.
They have been in my collection for many years, but now its time to part.
Time for others to enjoy them.

(Instead of posting which ones are being sold and which i’ve still got on this page i’ll make another post)

I started collecting when i studied computer sciences.
It’s a wonder my parents attic wasn’t collapsing.
(They let me store many computers on their attic, let me run a mainframe in the house (previous post) and let me have computer-parties (pre-lan) in their home. (They even left, and gave me the space) .. 15+ teens with computers … there was a pingpong table in the livingroom (besides the other tables in the house ) For all computers.

Then i’ve got even more, when living on my own. (At some point about 140. )

A few years later i got rid of uninteresting computers (to my taste at that time) and incomplete ones. Then i filtered-out the non working.

Still leaving with a lot of computers, i kept these for many years.

Now i only want the ones i’ve worked with, or are special to me.

My first computer was a Commodore Vic-20. Friends had the popular C64. So i kept 2 of both.
In Junior Technical School i’ve used the BBC Acorn a lot (Funny story below)
My then friend Richard had a Atari ST, loads of fun we had with that machine, so i’m keeping a Atari 1040STf.
Another friend used a Apple SE, so that one i also keep for now.
I’ve been programming a lot on 80×86, the first dos PC’s, i’m still looking for a old machine (Laser XT) which i used way back then. But for now i’ve got a Sinclair PC200.
I’ll keep a old Commodore PET 2001, because its cute.
Besides having a cute PET, i’ve got a Holborn System. Made in Holland (Enschede), there are only a few left according to some sites: only 200 made! (Holborn means Holland Born) One of the inventors was from Holten, my birthplace. (Polak)

At school we kept a list of everyone’s collection.

Soo .. the story about the BBC Acorn.

When i was at school outside study hours, i went to the computer lab.
This was one classroom with about 16 BBC Acorns and a master (teacher station). When they saw how enthusiastic i was, i got the key to the classroom. I even got access to the master system. And after a little hacking i’ve gained access to the teachers files.
There was a simple network system, i think it was called Econet.
The teachers system was the only one with a disk station.

I liked the ‘highres’ line graphics you could make on the machines. (640×256)
So i’ve wrote a lot of programs using this mode.
I even wrote a program which drew a 3D robotarm on screen using wireframe graphics.
At that time my mathematics scores where .. bad.
Wasn’t interested i think.
But drawing 3D robotic arms are not possible using mathematics, like using sinus, triangulary etcetera.
So when my mathematics teacher saw my program, he didn’t believe me.
So .. fooling around in the computer lab, i missed start of classes. And later on .. worse .. i almost was not allowed to do my final exams.
I was late several times (and one of the first to leave, …. straight from and to the computer lab. )

I’ve got some programs printed on paper, i will use my leftover BBC Acorn (or a emulator) to capture some screen examples.

Sold stuff

UPDATE : Selling a lot, but i’ve bought some others between 2020-2023

SDK-85
Laser Xt/3
80386 DX

Also a “new” 1084 monitor (CRT for a Commodore 64)
Now i have to look for a VGA Crt to get old vga-register manipulation programs working.

Computer

6502 news

2022-08-29 fash

Divers new additions to the 6502 project

Above is my design for a hex keyboard to enter opcodes in hex using a simple monitor program.
i used a 74ls922 which can decode a 4×4 matrix. I’d rather had a 74ls723 which can encode 20 keys.

Nowhere to be found. So i have to think of a new plan.

Now it is configured as follows:

C	D	E	F
8	9	A	B
4	5	6	7
0	1	2	3

When pressing the alternate key

addr (to implement)	run (1/2 implemented)	reset (to implement)
		step instruction (to implement)
		memory next
		memory previous

PCB design for matrix hexboard with place for notes

Meanwhile i’ve ordered new keys (the ones i’ve been using for my photomanager project and wnat to have a setup like this:

?	?	addr	run	reset
C	D	E	F	?
8	9	A	B	step
4	5	6	7	mem next
0	1	2	3	mem prev

When you want to show the status of busses and alike, you can’t use a led and restistor directly on the bus, it will require too much current.
So i’ve been using below schematic which uses a darlington array.

Now i can display databus, address bus and i’ve been using this for address decoding logic and hex keyboard.

I’ve implemented a second VIA chip, and ordered components to amplify the SID sound part

Computer

C64 Cartridge

2022-08-19 fash

Got IC Sockets in today, together with other goodies.

So i soldered the C64 Cartridge print.

Putting a bin on the eeprom

sudo minipro -p AT28C64 -w 8kcart.bin

Welll .. allmost working.
Some strange artifacts, but is running.

Prutser ..

Tag Archives: retro

Hercules to VGA

7 segment displays/keyboard decoders in SDK’s

SDK-85 searching archives

SDK-85 in 2022

6502 Update

Cool terminal combo

Eurocards

Selling a lot of my computer collection

6502 news

C64 Cartridge

"If something is worth doing, it's worth overdoing."