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1
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3answers
146 views

Did any RISC CPU ever take more than one clock cycle per instruction?

Classic RISC CPUs like ARM and MIPS basically offer the trade-off: simple instruction set, but instructions execute in one cycle for good overall performance. (It gets more complicated in later times, ...
-1
votes
2answers
81 views

What was the first introduction of callback concept of programming?

Although I seriously code with computer languages in general since 2010 and as an amateur programmer with programming languages in particular since 2015 (primarily Bash and JavaScript imperative ...
7
votes
3answers
740 views

Why did early arcade games use vertical displays?

Surprisingly many early arcade games, such as Pac-Man, Galaxian and Galaga, mounted their displays vertically, in portrait rather than landscape orientation. (From the perspective of the electronics, ...
1
vote
1answer
38 views

Looking for a Ninja PC Game where hero arrives in hang glider

I'm looking for a game I played in the early 90's on a Tandy computer. Here are the facts I remember by decreasing order of certainty : The beginning of the game is the hero arriving in an hang ...
1
vote
2answers
85 views

386 laptop: reads MBR, cannot boot DOS 6.22

I am trying to boot 386 laptop from a CF card. I've prepared image by installing DOS 6.22 in VirtualBox, and then burning image to a CF card. Image boots just fine in VirtualBox. CF card with the ...
-1
votes
1answer
45 views

386 PC: reads MBR, cannot boot DOS 6.22 [duplicate]

I am trying to boot 386 laptop from a CF card. I've prepared image by installing DOS 6.22 in VirtualBox, and then burning image to a CF card. Image boots just fine in VirtualBox CF card with the ...
4
votes
1answer
115 views

How did the Donkey Kong arcade hardware provide 128 sprites?

According to https://en.wikipedia.org/wiki/Donkey_Kong_(video_game) The Donkey Kong hardware has the memory capacity for displaying 128 foreground sprites at 16x16 pixels each and 256 background ...
2
votes
2answers
76 views

6502 interrupts when RDY is low

If the NMI line goes from high to low when the RDY is low, is the NMI detected, so that when RDY goes high, NMI is performed ? Or is the NMI discarded when it occurs when RDY is low ? (In case of ...
3
votes
1answer
51 views

How much control of TRS-80 Model III disk drives was possible from its Cassette (ROM) BASIC?

How much control over the TRS-80 Model III's floppy drive controller can be effected via relatively simple commands, typed into its built-in Cassette BASIC? My understanding is that general usage of ...
-1
votes
1answer
106 views

Commodore – The Inside Story [closed]

Commodore – The Inside Story, by David Pleasance, who was a manager in Commodore UK. Sounds like a very interesting book, supposedly available, but when I look on Amazon, hoping in particular for the ...
6
votes
2answers
148 views

In an Apple IIc, how is memory beyond 128K addressed?

I always thought than in a memory-expanded Apple IIc fitted with firmware version 3 or 4 and an Apple-built memory expansion, the extra memory above and beyond the first 128K is connected in a way ...
8
votes
1answer
1k views

Looking for a 90s Macintosh game

I'm trying to find an early to mid 90s Macintosh game. It was a side scrolling shooter in the style of R Type. You flew a spaceship that looked vaguely like the USS Enterprise from Star Trek, albeit ...
2
votes
1answer
56 views

Apple IIe auxiliary RAM bank select register address — C073 or C07X?

On the Apple IIe system, an "auxiliary RAM" card may be present which expands the built-in 64 kB RAM. When using an aux RAM card which has more than 64 kB, the auxiliary RAM bank in use can be ...
4
votes
2answers
548 views

Adding a register to the accumulator in 6502

In the past, the only assembly programming I've done has been a tiny bit of ARM, and then a larger game project in 68k. In 68k I was used to being able to do things like add.l d0, d1 to add the ...
19
votes
7answers
4k views

Which 8-bit computers were used in German schools in the 1980s?

In the 1980s, each country had a particular brand of computer that was most commonly used in schools; often, there was pressure to go with a local manufacturer. In the US, the Apple II. In Britain, ...
8
votes
1answer
2k views

NES chips usage

I am curently studying NES architecture to create a NES emulator. While looking up the NES motherboard schematics (https://console5.com/wiki/Nintendo_NES-001), some of the chips usage are not clear to ...
7
votes
4answers
330 views

What's the easiest way to bring up a MACLISP REPL on modern machines?

I'd like to bring up an old (pre-1975) LISP REPL so I can type things in and see how it behaves. MACLISP would be good but I'm open to other, similar LISPs, even as far back as LISP 1.5. What's the ...
17
votes
3answers
2k views

What are the difficulties in putting old AT style motherboards into modern ATX cases?

I have several 286, 386 and 486 motherboards that I would like to use. My problem is that while I have all of the components to make them functional, I don't have spare cases to put them in. Ideally,...
5
votes
3answers
646 views

Indirect addressing using address bits as marker (tagged address)

After reading about the Signetics 2650, and being a bit familiar with the HP2100's, I'm curious how common the style of "indirect addressing via the address value" instruction was at the time? CPUs ...
1
vote
1answer
104 views

What is the format of the Apple 1 character set ROM?

What is the format of the video character ROM used in the Apple 1?
15
votes
2answers
1k views

Why did MC6809(E) require two-phase clock consisting of two square waves shifted by 90°?

Usually when talking about two-phase clocks in early CPUs, one means this type of clock, that consists of two non-overlapped pulses. Examples are MC6800 clock (page 3) or i8080 clock (page 6). Many ...
5
votes
1answer
149 views

SID, sampled sound and bad lines

The SID could play sampled sound by poking a click into the chip at an appropriate frequency, and some Commodore 64 games like Ghostbusters and Impossible Mission did this (though only for a few ...
2
votes
1answer
138 views

What was the die size of the 6581 SID?

The MOS 6581 SID, the original version of the sound chip in the Commodore 64, was according to Wikipedia, 'produced in 7-micrometer technology to gain a high yield; the state of the art at the time ...
13
votes
3answers
386 views

History of ARM Linux and FPA

ARM Linux, at least Debian was traditionally (pre eabi) built for the FPA floating point unit*. Unfortunately under old ABI it was not easily possible to mix soft-float code with FPA code. The result ...
3
votes
1answer
133 views

ABEL HDL: What was the purpose of the 'flag' keyword?

Some context first: ABEL (Advanced Boolean Equation Language) is an old hardware description language which has been mainly used in the 80/90s to program CPLDs. Unfortunately I have not found any ...
20
votes
3answers
2k views

Why was it not possible to cost-reduce the Amiga 500?

According to 'Commodore: The Final Years' (whole trilogy highly recommended, BTW), page 129, 'Jeff Porter realized it would not be possible to significantly cost reduce the Amiga 500 to get it into ...
2
votes
1answer
172 views

Panasonic KX-W50TH Data Transfer

I have a Panasonic KX-W50TH thermal typewriter with a nine pin serial interface port on the side. I have a RP-K105 interface connected to my Windows 10 computer using a Sabrent USB to Parallel cable. ...
18
votes
7answers
2k views

Cost of unrestricted sprites

All the game consoles of the second through fourth generations, and several early home computers, had sprites, which were valuable though costly, e.g. the VIC-II spent 2/3 to 3/4 of its area on ...
8
votes
2answers
247 views

Were expansion slots fundamentally incompatible with FCC regulations?

The Apple II provided the ability to connect to your TV (as opposed to purchasing a dedicated monitor). However, at that time, the FCC criterion for applying stringent RF emission limits was 'device ...
15
votes
1answer
1k views

Can I use all features of a Commodore 1571 external drive from a C64?

I know that the Commodore 1571 drive works perfectly well with a C64, since the 1571 will detect it is connected to a C64, and will enter 1541 emulation mode. After which, the 1571 just behaves as a ...
13
votes
5answers
2k views

Was the MC6800 a PDP-11 or PDP-8?

According to Gordon Bell, the 6800 was based on the PDP-11. According to Chuck Peddle, it was a PDP-8. Can anyone with knowledge of the PDP's pass judgement?
15
votes
1answer
1k views

How did the 6502 ALU perform a decrement?

Assuming that this diagram is correct: Instructions like INC, INX, and INY can easily perform increment using ALU sum with data on B input, 0 on A input and carry_in set. But how do instructions ...
2
votes
1answer
251 views

How I can install Windows 98SE in Hyper-V, but can't run it after

Create the Gen 1 machine with less than 512MiB Ram (above requires you to put MaxFileCache=524288 and MaxPhysPage=40000 in the system.ini later). Add either a virtual or physical IDE drive (physical ...
9
votes
8answers
2k views

Variances in Basic highest line numbers

I used to wonder why different versions of Basic on 8bit machines would impose different limits on the highest line number permitted. I should point out this excludes any trickery to manually change ...
2
votes
1answer
117 views

BBC Micro default Mode specifications vs reality of production models

Note this only appplies to the Models AandB as the Master had configuration set in NVRam. One of the BBC's initial listed requirements for their computer to Acorn was a default of Mode 4 : " START-...
6
votes
0answers
113 views

How did the Tandy 1000 select its drives?

I am trying to use some Tandy 1000 drives with a SuperCard Pro and have encountered some anomalies using them as "standard" floppy drives. It appears that with the original (or at least, working and ...
0
votes
1answer
178 views

How to make old keyboard more responsive

Have an old (HP Omnibook from 1993+) keyboard that feels too sluggish. It takes a little bit too much effort to press the buttons. There is no difference between individual buttons. This particular ...
2
votes
4answers
338 views

What 8bit home computers did not have a supplied intro tape [closed]

As per the title, we are obviously referring to machines that had cassette audio tape as their default medium even if other media was supported via expansion. To be clear I mean what was "in the box" ...
5
votes
2answers
1k views

How did the BBC sideways ROM software for the AMX mouse process the user port input data to determine x and y movement?

This mouse plugged into the user port on the underside of the BBC micro models. The mouse came with software in the form of a sideways ROM which provided APIs, CLI commands for own programs as well as ...
-1
votes
1answer
105 views

Fan for old socket A Athlon cooler [closed]

I put together a retro gaming setup with a 2000ish spec (can post specs if required) and it's come together pretty nicely except the CPU fan is insanely shrill (it's a Coolermaster something). If I ...
2
votes
1answer
124 views

How can I make an external PSU for an Apple IIc?

I purchased an Apple IIc from an auction site, but it came without the external power supply unit. While this question and its answers describe how to open up the IIc and use alligator clips to power ...
12
votes
4answers
2k views

Accelerators for Z80 micros?

I am familiar with the various accelerator products that were developed over the years to improve the performance of popular 6502 home micros. A short list of the particularly well known devices would ...
10
votes
1answer
699 views

Why did the ZX81 16K RAM pack use two PCBs?

The ZX80/81 16K RAM pack used two PCBs joined with a connector in the middle. I'd initially assumed this was due to reuse of the original 3K RAM pack case (which has a single PCB and uses static ram)...
7
votes
3answers
284 views

What home computers offered an adjustable tape baud rate

By the title I mean a built in option rather than a software or hardware add on and saving / loading to regular domestic audio cassette tape. We should exclude all third party type loaders from this ...
9
votes
3answers
728 views

Cost of dynamic versus static RAM in the early days

Early pioneers building memory cards for personal computers, tended to use static RAM, because it's quite a bit easier to get to work. Later, dynamic RAM became de rigueur, for the simple and ...
22
votes
1answer
424 views

Reconstruct the loop from “The Story of Mel”

From Ed Nather's hacker-epic "The Story of Mel" (using the original paragraph-formatting to save space in this question): The firm manufactured the LGP-30, a small, cheap (by the standards of the ...
2
votes
1answer
114 views

Vic-20 tape I/O dependence on CPU speed?

As I understand it, the Vic-20 reads and writes the cassette deck by the low-tech expedient of just using the CPU to bit-bang a one-bit serial line. This presumably means that for a given code ...
24
votes
4answers
8k views

8080 vs. 8086 - Are 16 Bit CPUs bloaty by nature?

In comments to a parallel question (Why was IBM BASIC so Huge?) one point discussed is code density of 8 vs. 16 bit CPUs. Some assumptions were that 16-bit must be more bloaty due to its need for an ...
4
votes
0answers
97 views

Did Hayes and/or other modem companies ever add TDD capability to their modems?

A Telecommunication Devices for the Deaf (TDD, aka Text Telephony (TTY)) was an early modem capability to allow deaf people to use telephones by including a keyboard and output device (such as ...
8
votes
3answers
2k views

Did multiplexed address/data lines make memory access slower?

Looking at the pinout of e.g. the 8088, it multiplexes the data lines onto eight of the address lines; presumably the designers judged that being able to squeeze the chip into a 40-pin package, would ...

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