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10
votes
3answers
1k views

Why did blanking of screen on C64 SAM enable better quality speech synthesis?

There's this old piece of software still present in today's Windows called SAM that enabled C64 to speak. I remember that we could choose either screen on and worse speech quality or screen off and ...
20
votes
4answers
2k views

Was the design of MS-BASIC for 6502 based on MS-BASIC for 8080?

Looking through the source code of the 6502 MS-BASIC, certain parts of it seem more reminiscent of how things would be done on the 8080, then on how they should be done on the 6502. Code to find a ...
7
votes
1answer
399 views

Determine Character Encoding used on HP 9000 Model 310 running BASIC 5.1

With the help of this community, I was able to copy and emulate a HP9133 HD using Hpdir and Hpdrive. Now, I want to edit, or at the bare minimum, read the programs on the HD. I have extracted the ...
1
vote
1answer
204 views

Is this a UART chip? [closed]

Based on my understanding, a UART chip is a chip that exists on a serial card, and it is responsible for the actual sending and receiving of data over the serial port. I want to see what a UART chip ...
21
votes
3answers
4k views

Does an ISA card have a fixed memory address?

A PCI card does not have a fixed memory address, the PCI card specifies how much memory it wants, and the OS will assign whatever address it wants for this memory, and will set this address in the PCI ...
11
votes
5answers
2k views

Mapping more than 64kb of address space

I'm planning out a 6502 homebrew build but seem to be stuck in the issue of buying parts. My plan is to extend the addressing capabilities of the 6502 by giving myself 64kb of RAM, and another 64kb of ...
14
votes
1answer
592 views

What's the deal with System/360's “USASCII” mode?

The original System/360 architecture had a bit in the Program Status Word that would select an "USASCII" mode rather than the usual EBCDIC. Setting this bit changed how the BCD arithmetic operations ...
6
votes
1answer
932 views

How was the Microsoft PDP-10 8080 emulator developed? [closed]

Altair BASIC, the first version of Microsoft BASIC, was developed using an Intel 8008 emulator, modified to emulate an Intel 8080, running on a PDP-10 computer. This emulator was originally designed ...
7
votes
4answers
878 views

How were interpreters loaded into computers?

I have been learning about PCs, the first of which was the Altair 8800. So that users could run programs, Micro-Soft created a BASIC interpreter to allow the program to be mapped to processor ...
2
votes
2answers
356 views

Programming on Macintosh Centris 610

I just bought a Macintosh Centris 610 and I'm trying to do some C programming on it. But I can't find the terminal and someone told me there isn't a terminal on classic MacOS. My goal is to have a ...
24
votes
2answers
2k views

Why does waggling the joystick of a C64 cause errors loading from tape?

When loading a game from the tape drive on a C64, if you wiggle the joystick around too much the program will not load correctly. Is there an explanation for this? EDIT: Perhaps someone can try to ...
5
votes
1answer
347 views

How were the electronics in the Elektronika IM (Электроника ИМ) designed?

Elektronika in the Soviet Union created a series of handheld games in the 80s (Электроника ИМ) similar to the Nintendo's Game & Watch. How were the electronics in these games designed, especially ...
17
votes
3answers
3k views

Do you need to allocate memory before you use it in MS-DOS?

In modern operating systems (for example: Windows), you can't access a memory location before you allocate that memory location to your program (or else a segmentation fault will occur). I am ...
37
votes
4answers
6k views

What's with the Atari 2600 colors on SECAM?

On this picture below you can see that the Atari 2600 graphics are rather colourful, and some games like Pitfall! I think use the many shades of each colour and have rather good graphics for the 2600. ...
11
votes
4answers
1k views

Looking for an easy to use Commodore 64 disk/sector editor

First, let me say I understand that 'recommendation style' questions can be very subjective, but I believe there is enough value in a few good beginner resource pointers that others could benefit from ...
16
votes
6answers
1k views

C64 BASIC: How to suppress the '?' sign when using the INPUT command?

When you are getting INPUT in Commodore BASIC it always adds a question mark at the end of the string you want to show. Is there a way to suppress the question mark when using the INPUT command?
13
votes
4answers
1k views

6502: What does the Predecode Register exactly do?

When you look at this block diagram you can see a 'Predecode Register' I suppose that the Opcode is already a 8-bit Number (D0-D7). So what was the purpose of the Predecode Register. Did it really ...
4
votes
1answer
513 views

Anyone know the specific differences between a Northgate Omnikey 101 and 102?

Quick background-- I really love old school springy/mechanical keyboards. I haven't used one in years but it's been on my "to purchase" list for years to get an IBM Model-M for my work. After doing ...
5
votes
1answer
424 views

Cost differential between 2 and 4 MHz RAM chips in 1982

The most common speed of the 6502 was 1 MHz, allowing the use of 2 MHz RAM chips (half the bandwidth went to the video chip to refresh the screen). In 1982, the BBC Micro shipped, with double speeds ...
12
votes
11answers
2k views

Which pointing devices were used by early laptop computers?

I've started reading this article on the history of the ThinkPad. In it, the TrackPoint (pointing stick/"nipple" mouse) is heralded as an important innovation in the design of portable computers at ...
8
votes
1answer
251 views

QEMU with SunOS 4 - how to transfer files

How do I transfer files between the host and the guest when using SunOS 4 under QEMU? I have followed this guide: https://en.wikibooks.org/wiki/QEMU/SunOS_4.1.4 But when I try to rlogin or rcp, I get ...
22
votes
4answers
4k views

Z8410 DMA chip as GPU?

There are basically two ways to design a 2D graphics system: Provide lots of hardware support in the form of tiles, hardware scrolling and sprites, to put together each frame on the fly from a small ...
9
votes
1answer
477 views

How can I tell if an Apple II disk image is bootable?

I have around 500 floppy disk images from an Apple II and IIgs BBS/usergroup that closed down recently. Some of the disks are bootable, but many aren't. Is there an easy way to tell if a disk boots ...
13
votes
7answers
2k views

Z80 and video chip contending for random access

Back in the 8-bit days, I used 6502 computers, where the story about memory access was easy to understand. RAM chips of the late seventies and early eighties could do 2 MHz (or a bit more e.g. 2.6 in ...
11
votes
2answers
638 views

Why does this BASIC program keep restarting?

Here is a BASIC program for the Commodore 64, which should load the LIB file from the disk, and then stop. Yes? 5 PRINT "LOADING..." 10 LOAD "LIB",8,1 20 STOP the LIB file is 102 bytes long and is ...
5
votes
4answers
734 views

RAM contention and what counts as different banks

From https://en.wikipedia.org/wiki/ZX_Spectrum_Contended_Memory "Contended memory space, on the other hand, is shared between the ULA and the Z80 and the ULA has higher priority. Contended memory ...
5
votes
1answer
281 views

Collection of older EPROM IC's

I acquired a collection of older EPROM IC's and am wondering what the rarity of them are or if they are rather common. Do people collect these items? 89142 NM27C512Q ~~ B9212 NM27C512Q ~~ B9312 ...
7
votes
2answers
1k views

C64: Strange Behaviour on Control Port 1

I wrote this little Basic program to get Joystick input from Control Port 1. I know that this method is very strange and is better for keyboard input. 20 get a$ 30 if a$="" then 20 32 b=asc(a$) 33 ...
10
votes
4answers
1k views

Video chip for hypothetical 1988 arcade game

I have a project where I aim to create a retro arcade game cabinet, the technology would be ~1988. For now I am planning to only simulate the system on my PC in order to develop the game. The ...
8
votes
1answer
450 views

Is it possible to chain TMS9918 chips to get better graphics?

I'm considering creating a retro system but without requiring the sacrifice of any retro machine in order to get parts. The TMS9918 chip seems the only "generic" retro graphic chip, all other chips ...
5
votes
2answers
931 views

How hard would it be to port Amiga OS4 to x86 or ARM?

This question was raised on Facebook a few hours ago. Some say it's possible, others say impossible. What do you experts say?
6
votes
1answer
562 views

What is the title of this Macintosh programming book?

Back when Mac OS was called "System" and preemptive multitasking was a distant fantasy, I had a small collection of Macintosh programming books. For the life of me, though, I can't remember what one ...
15
votes
1answer
620 views

Where are the blueprints of MOS chips?

Atari historians have been able to find documents and tapes of chips and hardware developed at Atari. E.g. http://atariage.com/forums/topic/154479-new-gtia-chips/ . Nothing like this is happening ...
30
votes
2answers
4k views

C64: Why is POS(π) faster than POS(0)?

According to this article: german C64 Wiki article about the POS() command POS(π) is 20 % faster. Although in my experience it is ...
12
votes
2answers
1k views

PET space arcade game with surprisingly good graphics

We had PET computers in my high school, 4032's IIRC, and a few classic games to go with them - the excellent Space Invaders port, Star Trek of course, and a few others. These all used PETASCII for ...
10
votes
1answer
1k views

What is this extra lead in my monitor cable?

I have a breadbox Commodore 64 with a Commodore 1702 monitor. My monitor has three RCA-style inputs on the back: Audio (White) Luma (Yellow) Chroma (Red) I purchased a cable which claims to be an ...
5
votes
1answer
251 views

Primary manufacturers of picture tubes for early monitors

Which companies were the most important manufacturers of picture tubes for monitors (both monochrome and color) in the seventies and eighties? That is, it's easy enough to find lists of monitors by ...
5
votes
1answer
305 views

Cyrillic Ж on IBM 1620?

Wikipedia says that The IBM 1620 Model I used the Cyrillic character Ж (pronounced zh) on the typewriter as a general purpose invalid character with correct parity. The Model II used a new character ❚...
7
votes
6answers
2k views

How can I copy files from a Compaq Deskpro?

I have a Compaq Deskpro EN 6266 Deskpro EN PII 266 Computer, pictured below. When I try to insert a 4.7 GB optical disk, the PC stops. When I use a 720MB optical disk it says that I don't have ...
4
votes
1answer
304 views

Need help identifying an Apple IIc game/possibly educational with a top-down view

Played it around the end of the 80's but most probably developed between 1981 and 1986. You had control over a person/avatar (not stick figure like, more plump looking) and could walk from scene to ...
4
votes
2answers
371 views

Getting a disk image off of a HP 9133 drive

I have a HP 9133 combo disk drive connected to an HP 9000 model 310 computer running Basic 4.0. This setup is used to control a few machines, and does not have a floppy inserted. The hard drive is ...
9
votes
3answers
1k views

Game cartridges on the S-100 bus?

Many Z80 computers in the seventies and early eighties used the S-100 bus, into which you could plug many kinds of expansion cards. Would it have been possible to plug suitably designed game ...
8
votes
1answer
234 views

Was there an interactive macro/scripting language named PAGEN?

In a BESM-6 disk image I can see bits and pieces of something that looks like a strange interactive scripting language: [start of disk block] <LET=P11=%X01 <IEQ=P11=%377 <LET=P11=1 <END &...
3
votes
2answers
494 views

C64, basic v2, DATA strange behavior

I have the following code line: 0DATA"-+-+-" Here "\" and "/" are the ASC codes 205 and 206. I get a syntax error: ?SYNTAX ERROR IN 0 READY. As I can remember, there was same special in the ...
8
votes
2answers
1k views

Can the ADB keyboard and mouse be converted to the 128K Macintosh?

As you probably know, the original Macintosh 128K, 512K (Fat Mac) and the Macintosh Plus (IIRC) have a different keyboard and mouse connection than the later ADB versions such as the Macintosh SE ...
17
votes
4answers
4k views

How fast is memcpy on the Z80?

I gather the fastest way to implement memcpy (copy a certain number of bytes from one place in memory to another) on the Z80 is to use an instruction called LDIR. But how fast is the result, when ...
9
votes
3answers
472 views

Copying disk image from HP 9122D drive

I have a HP 9122D (EDIT: its actually a 9133) combo disk drive connected to an HP 9000 model 310 computer running Basic 4.0. This setup is used to control a few machines. The hard drive is getting ...
8
votes
2answers
1k views

What was the first commercially available computer with ECC memory?

In the early days of computing, memory error detection and correction was either non-existent (Wikipedia tells of Seymour Cray famously saying "parity is for farmers" when asked why he left it out of ...
20
votes
2answers
3k views

How did Z80 multiprocessing work in the Namco Galaga hardware?

Galaga was a popular arcade game developed and released by Namco (Midway in N. America) in 1981. It had amazing, fast, smooth 2D-sprite graphics, and relied on Namco hardware that utilized 3 Z80 CPUs ...
7
votes
3answers
812 views

Serial Receipt Printer Garbage

I connected a vintage serial matrix receipt printer (Datamega DPN-233) via FTDI to my MacBook's USB. It performs its own self-test without problems, prints an example and the RS 232 configuration (...

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