151
votes
Why did some early CPUs use external math chips?
Simple: Complexity.
A 8088 had about 29,000 transistor functions, while an 8087 with 45,000 is almost double that. Integrating the FPU within the CPU would have made it three times as big, putting ...
- 213k
66
votes
Accepted
Why were chips socketed in early computers?
Caveat: It might be useful to distinguish between high volume low cost computers (like the mentioned CoCo) and low volume high cost machines (like Intel boards - or workstations). I assume the ...
- 213k
65
votes
Why did some early CPUs use external math chips?
So these math chips (I assume you're talking about floating point units, such as the 8087 and other coprocessors) were not always/usually included in the CPU because they were not required by most ...
- 38.2k
53
votes
Accepted
Why did some early CPUs use external math chips?
Another point not addressed in the existing answers relates to the latency associated with accessing an external coprocessor.
The first math coprocessors, while much faster than doing the same work ...
- 1,734
48
votes
Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?
After some more research, I believe I've stumbled across the real answer: The VIC-II and SID used a larger process node size because Commodore's fabrication line circa 1981 was uniquely positioned ...
- 719
39
votes
Why did some early CPUs use external math chips?
It seems to me there are a number of factors involved, some of which have been addressed in other answers:
design complexity
cost (which largely results from the complexity)
feature necessity
time-to-...
- 118k
30
votes
Accepted
Were there any enhancement chips that vastly outperformed the main CPU?
I think the SA-1 chip in various late-era Super Nintendo cartridges (eg. Kirby Super Star, Kirby's Dream Land 3, Super Mario RPG) would qualify.
Here's what Wikipedia has to say about it (emphasis ...
- 6,351
29
votes
Accepted
Graphics chips in 1980
There were. A couple of examples are the Motorola MC6845 and the MC6847. These chips were flexible and allowed various resolutions and colors depending on how they were implemented.
The MC6845 was ...
- 4,643
28
votes
What exactly was the Amiga Ranger?
Ranger was to be the next generation Amiga, which the original West Coast Amiga engineers began working on in 1986-87, following the release of the Amiga 1000. Jay Miner improved the graphics chipset ...
- 60.1k
24
votes
Accepted
Is there any advantage of a ceramic microprocessor over a plastic one?
One factor is indeed better heat dissipation properties of the ceramic housing. In those times both Z80 and 6502 were NMOS and had considerable heat release, so better heat transfer properties of ...
- 10.2k
24
votes
How much did the 6502 and Z80 cost?
The MOS 6502 (1 MHz) was introduced in 1975 for a price of $25. Then in 1978 MOS agreed to sell the 6502 (1.79 MHz) and an IO chip to Atari for $12 per set (because the production cost was $4).
In ...
- 17.4k
23
votes
Accepted
Who made the Atari 2600 TIA video chip?
The TIA chips were manufactured by a number of different companies, in a number of revisions over the years; the Atari Compendium’s page on the topic lists:
American MicroSystems (“AMI” marking on ...
- 118k
23
votes
Accepted
Reason for gold lines on old ICs?
It's a ground wire. The way ICs were manufactured back then had the metal cover placed over the die as the last step, and grounding it helps protect the die from static shock and interference.
If you ...
- 15.1k
22
votes
Accepted
Why did the PlayStation 2 implement backward compatibility that way?
Probably because it was the only way to get 100% compatibility with the old software library, which was required while most PS2 titles weren't developed yet. No one wants to buy a machine without ...
- 10.7k
22
votes
Accepted
Who owned the rights to the TIA chip?
The TIA was designed by Jay Miner while he was working at Atari. I'd be very surprised if Atari did not hold whatever rights could be held.
That being said, the rights that could be held to an IC ...
- 9,820
21
votes
Graphics chips in 1980
I designed a color graphics card for the Z80 ECB bus back in 1984 or so, based on the 6845.
The 6845 was "just" a timing and addressing generator. It was meant for character-based displays. So it ...
- 2,320
20
votes
Accepted
What is the Kelly chip?
The question should rather be: "What could it have been?" - It never made it into an existing machine. According to some Internet lore, Kelly would have been the A3000+'s/AA3000's RAMDAC (digital ...
- 33k
19
votes
Why were chips socketed in early computers?
One reason to use sockets at the beginning of a production cycle is to make it easier on the service technicians.
At one company making computer terminals, the techs would identify a bad chip and ...
- 747
19
votes
Accepted
When did half-bad RAM chips stop being available?
Sinclair's use was a very unique case in a very specific situation that never occurred again later on.
Production side:
There were many more manufacturers of chips back then.
The ones that wanted to ...
- 213k
19
votes
Accepted
How did the Fairchild Channel F provide a 2K frame buffer?
ChannelF uses 4 MK4096 4k * 1bit chips (4 middle-left rectangles in the schematics).
The framebuffer is write-only, the CPU cannot directly access it through memory accesses. The CPU has no address ...
- 3,447
18
votes
Accepted
Why did Commodore not upgrade OCS straightforwardly to 32-bit architecture?
One could just as easily ask why it was not extended to 64 bits, or even wider. Well, if you ignore backwards-compatibility and cost, yes, it could have been.
I'll pretend we can ignore backwards-...
- 10.8k
17
votes
Accepted
How much did the 6502 and Z80 cost?
The answer from snips-n-snails gives prices for times close to the release of the chips and at dates of significant sales. But note that prices were effectively in freefall, and that every quarter ...
- 12.8k
17
votes
Accepted
Cost of unrestricted sprites
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 ...
- 16.7k
16
votes
Accepted
Why are the internals of NES Gamepaks so small compared to the case?
Under the hood, the NES was almost identical to the Famicom, its Japanese counterpart released in 1983:
image source
The Famicom console itself was much smaller that the NES, and it had a ...
- 5,404
16
votes
Accepted
Did the transmeta processor architecture work by binary translation?
In the Wikipedia article on Transmeta there's a good example for the Code Morphing process, taken from a PDF document (Wayback archived) with even more details:
The operation of Transmeta's code ...
- 26k
16
votes
Why did the VIC-II and SID use 6 µm technology in the era of 3 µm and 1.5 µm?
In short, 3 µm looks like it was available at the time,
The questions are rather:
to whom it was available and
is it worth the investment.
Processes aren't anything you'd buy from some supplier but ...
- 213k
16
votes
Accepted
How were 4-digit IC part numbers assigned?
It seems that integrated circuits of the 1970s tended to have 4-digit part numbers.
Not really. Anything from letters to numbers and 3 to 7 characters have been used. Even with numbers like 7400, the ...
- 213k
15
votes
Accepted
Number of transistors in the C64
Logic
6510: ~3500
VIC II: ? (est. 5000)
2x CIA: ? (est. 2000)
PLA: ? (est. 1000)
SID: ? (est. 2000)
commodity chips: ~500?
Memory
64K DRAM: ~526000 (one transistor per bit, one transistor per row ...
- 3,804
15
votes
Where are the blueprints of MOS chips?
MOS was renamed to Commodore Semiconductor Group (CSG) sometime after Commodore bought them in 1976. After Commodore folded in 1994, the CSG division was bought by its former management and renamed ...
- 4,517
15
votes
Accepted
What process node were 4k and 16k DRAMs first made at?
Intel manufactured its 1-kilobit 1103 RAM on an 8 μm P-MOS process.
Through most of the 1970s, DRAM was made from NMOS. The first successful CMOS memory was the Hitachi HM6147 SRAM, a 4-kilobit chip ...
- 8,549
Only top scored, non community-wiki answers of a minimum length are eligible