8

An 8-bit computer wanting 64K of RAM, could most straightforwardly use eight 64kx1 DRAM chips (64kbit, 1 data line). The Commodore 64 initially did this, but in the mid-80s, the cost-reduced redesign used two 64kx4 chips (256kbit, 4 data lines) instead.

It seems that something similar could have been done a generation earlier. For example, the Acorn Electron stuck to 32K to save cost. This was provided with four 64kx1 chips, requiring two clock cycles to fetch each byte from memory, which greatly reduced performance. If it could have used 16kx4 chips, it would seem possible to have achieved twice the performance without significantly increasing cost, yet this was not done, perhaps because such chips were not available?

Did any 8-bit computers use 16kx4 chips?

Improve this question
1
  • 1
    We used static 1k x 4's way back when, in lieu of 2102s :-)
    – Russell McMahon
    Commented Jan 2 at 7:47

1 Answer 1

Reset to default
10

Quite a lot - well, not many different, as those chips came at a time when computers with only 16 KiB as base memory - and that's where 4416 would have been a cost saver - were already on the way out. But some did use them. Incidentally some that became very popular - one way or another:

TI introduced the first 16 Ki by 4 as TMS 4416 in 1980. Still it took until 1982..84 until they became widely available (*1) and lower priced than four 4116. At that time 64 KiB RAM was the way to go for new designs, except for the very lowest end devices like TS 2068 and C16.

Likewise most 16 KiB computers didn't get any cost reduced revision at the time - the only exception might be a rather rare, late run of the Tandy Coco 2, which allowed the use of 4416 or 4116 (*2) - of course mostly fitted with 4416 :)

The C128/C128D is a exception as here it's about providing 16 KiB Video RAM (*3) in addition to 128 Kib main memory. Same the Philips. In fact, I would expect other MSX systems using them as well as two 4416 are the most basic (and lowest cost) fitting for a 99x8 videochip.

Of course there are as well oddities like the COL256 graphics boards for the NDR-Klein Computer which used 8(!) 4416 as video RAM.

*1 - Prior chip companies were happy if they could supply as many 4164 as requested, so no need to waste wafer runs on less demanded more niche devices.

*2 - Which make the beige TI 99/4A a very interesting case. Redone in 1983 to reduce cost, it still uses eight 4116 RAMs, despite TI having introduced the 4416 3 years prior.

*3 - Which in 1987, with the 128DCR got replaced by 4464 expanding video RAM to 64 KiB

Improve this answer
1
  • Good answer! Also, looking throughs ads at the back of Byte Magazine, 4416 seem to be surprisingly not cheap commodities. 1984-12, not listed. 1985-12, listed at $4.95, compared to 4164 same speed grade $.69. So just going by the cost of the chips (which admittedly are not the whole story, PCB area also has nonzero cost), it would actually be cheaper to provide 64K and ignore 3/4 of it, than to provide 16K with 4416s. Maybe that's why the Electron didn't use them.
    – rwallace
    Commented Jan 3 at 0:14

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .