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19

Which brand was most commonly used in West German schools? I know Commodore was big in Germany, which would make it a likely candidate, unless nationalistic pressure acted again? There is no simple answer. Not so much due any 'nationalistic pressure' (*1) but the fact that German schools are not run according to federal guidelines, but are managed on state ...


17

Hardware of this sort has to be able to cope with the worst-case scenario in any given dot-clock cycle. So it has to look at the top layer pixel, determine whether that is transparent, and if so go down to the next layer and repeat. Only when it finds an opaque pixel (which may be the background) can it determine the colour to drive the video output with. ...


14

They did, with the A600. But in true late-stage Commodore fashion, they screwed it up and made it more expensive. To cost-reduce an A500, you'd have to reproduce its spec on simpler silicon. The market wasn't interested in an 8 MHz 68000 in 1991/92: the PC had stolen all of the Amiga's thunder at commodity prices. The Amiga's niche silicon was just too ...


13

'Jeff Porter realized it would not be possible to significantly cost reduce the Amiga 500 to get it into the $250 retail price range'. They could have cost-reduced the A500 - perhaps even to $250 retail - but they would have had to make some compromises that (thankfully) they weren't willing to do. There were a lot of chips on the board. They needed ...


11

Having both an Oric Atmos and both a rubber Keyed and later plus Spectrum I can tell you the the Oric keyboard is vastly superior with a firm and positive action to each key. The feel of the keyboard is not too far off the feel of a CBM 16 or 64 but not as good as the Acorn range . The Oric physical size is also similar to the rubber keyed Spectrum too , ...


11

In general: memory needs stable address for a while. So the real access time is "time to address available + memory access time". If you use the CPU with a full address bus (Z80, 6502, ...), it can expose the whole address in one cycle, wait only "memory access time" interval, and you can read. On the other hand, let's take the 8085 CPU with a multiplexed ...


10

I can only speak for my own school, a Roman Catholic Gymnasium (i.e. highest-of-three-tiers secondary school, the word does not mean "gym" in German) in a small town near the former West German capital Bonn. But as far as I heard from others, this was sort of typical. We had one Commodore PET-2001 which the school got soon after it was available in the late ...


10

I did find some prices in BYTE: November 1975, page 91 2107 4Kx1 Dynamic: $19.95 (0.49 cents/byte) 2111 256x4 Static: -- not listed 1101 256x1 Static: $2.25 (0.89 cents/byte) April 1976, page 89 2107 4Kx1 Dynamic: $19.95 (0.49 cents/byte) 2111 256x4 Static: $7.95 (0.77 cents/byte) 1101 256x1 Static: $2.25 (0.89 cents/byte) Byte ...


10

According to EBU R95, the title-safe area for 576i format (corresponding to PAL SDTV) is 258 lines tall in each field. This is just large enough to accommodate the 256 lines per field that the BBC Micro uses. This is probably not a coincidence, as the BBC Micro was in part designed so that the BBC itself could use the micro for generating titles and ...


9

The Oric-1 improved somewhat over the ZX Spectrum's unusual chiclet keyboard. I guess the keyword too look for is "somewhat". Did it actually improve on the Spectrum's keyboard? If so, how? Well, much the way you already mentioned by having hard plastic caps instead of those rubbers. It gives a better feeling about pressing a key or not as all ...


8

There wasn't any master plan. Each school did its own thing, depending on the commitment of their teachers (or the lack thereof). Our school in Rendsburg/S-H got a few (5?) Sharp MZ-80K in 1981?, one MZ-80A a bit later (which featured an actually usable keyboard!) for programming in BASIC and Pascal. The MZs were followed by two Commodore PC-10 around 1985 ...


8

TL;DR Did historical sprite systems provide unrestricted positioning and overlap It wasn't unlimited and unrestricted, but limited by chip resources or memory bandwidth - or in case of inbetween systems by both. because the designers believed this was very valuable in reducing game development cost? No. Keep in mind, they often crippled machines ...


8

The 65816 does the same thing; the most-significant 8 address bits are multiplexed onto the data bus pins during the Phi1 half of each clock cycle, and it reverts to being a data bus during the Phi2 half. The WDC datasheet illustrates a simple external logic circuit which latches the address bits and isolates the data bus pins from a device responding ...


7

I believe this is the best place for PDP-1X documentation: http://bitsavers.trailing-edge.com/pdf/mit/rle_pdp1/ (Linking to a mirror because the main bitsavers.org is offline for the moment.) The 1975 memo PDP35, part 5A documents spheres and capabilities: A virtual memory space, any virtual processors (processes) that might be executing inside that ...


7

My firm designed microcomputer boards in the late 1970s to early 1980s, and we often had discussions about whether a particular design was going to use static or dynamic RAM. When you say "static RAM, because it's quite a bit easier to get to work", you also need to remember that the refresh circuits cost design time, chips, and board space. (No surface-...


6

In this document there is a mentioning of half a million dollars spent for designing the Z80.


6

The 8088 (and Z80 and 1802 and many other older CPU designs, including minicomputers and mainframes) required multiple clock cycles to run each machine code instruction. This was due to being implemented by internal microcoding, limited shared resources, or non-pipelined state machines, due to much lower transistor counts than todays processors. As long ...


6

It’s available directly from the publisher (the author’s own publishing company), including in electronic format (e-pub and Mobi).


5

The Vic20 was not the last consumer product to use static ram on the main system board. In the mid 90's a Socket 3 (486 class) motherboard was created by Ocean Technology octek.com - defunct. The HIPPO-DCA2 motherboard which required at least one 4MB 72-pin SIMM of something called DynamiCache RAM in the first 2 slots. DynamiCache was a built from high ...


5

There exists a copy of some draft requirements that the BBC had for the new machine. At the time, these had already been hashed out a bit with Acorn, so they match quite well with the resulting BBC Micro. A relevant extract: Keyboard: capable of generating all 128 ASCII codes. Positive action keys (not touch sensitive). ISO standard layout plus: (...


5

Why was Apple unable to comply with the limits when e.g. Atari managed it? Purely through engineering that Apple was unwilling to carry out. I have added a relatively detailed explanation of this to the Atari 8-bit article on the wikipedia. The long-and-short is that it wasn't the slots themselves that were the problem, but providing some sort of ...


5

if the programmer can guarantee that sprites will never overlap each other, and that they will be presented in numerically increasing order on each scan line. A hardware designer's response would be "programmers can't actually guarantee that." And they'd be right. The hardware would have to be designed to do something sensible if those rules were broken. ...


4

Supposing you have a fixed pixel output clock then the bottlenecks are: shifters, since you need to be sure you may need to sample any sprite at the current location; and either: bandwidth to fill those shifters, if you're a TMS descendant (which includes all 2d Sega consoles) and are fetching sprite contents from regular video RAM; or storage for what ...


4

From a previous question: What BBC Microcomputer features were requested specifically by BBC engineers? which references this BBC document: both pound sign and number symbol (hash) must be included ... the RETURN key will be a different colour from the rest; But that actually: and certain that the return key ended up being the same colour as ...


4

Two data points from North Rhine-Westphalia: About 1980 our small Gymnasium had a demo setup of original IBM PCs (with CGA/EGA graphics?) for some weeks, but then settled for a bunch of Apple II clones, maybe 16 devices. A neighboring Gymnasium had a Dietz minicomputer with four user terminals (plus one management terminal) at the same time, for several ...


3

I can answer half of that only: the BBC did often run into trouble, to the point that they cite the *TV command as early as Page 17 of the user guide: If the picture on your television screen is either too far up or too far down the screen, you can move the whole display with the command *TV. *TV 255 will move down one line *TV 254 will move ...


3

Intel very likely did this with surplus batches of ROM-equipped microcontrollers - eg if you look closely at the pinout of the 8031 vs 8051/8751, an 8051 wired up like an 8031 WILL behave as an 8031 no matter what is in the ROM/EPROM.


3

I have something to add. It's not exactly an answer, but it's too long for a comment. You are linking to 11Logo (which I put on GitHub, courtesy of CSAIL), but this wasn't the first version of Logo. It was first implemented on PDP-1 at BBN, and later updated for a PDP-10. The PDP-10 version was moved to MIT (the files still have a BBN copyright notice), ...


3

The other posts about hardware and gate costs better answer your question, but I'll add this as a counterpoint: A situation where a game programmer decided not to take advantage of hardware collision detection (in this case, for the Atari 8-bit port of Super Pac-Man): On the 400/800 I noticed that people knee-jerked toward using the player-missile ...


3

In the late 80's we had Apple IIs for 6502 assembler and DOS machines with amber monitors for Turbo Pascal and SPS programming. That was at some sort of high school with engineering focus in northern West Germany.


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