2114s were pretty dense and common. There were plenty of 16K S-100 boards with 2114s, and, of course Ohio Scientific. Two boards would give you 32K. -----Original Message----- From: vcf-midatlantic [mailto:vcf-midatlantic-bounces@lists.vcfed.org] On Behalf Of Joseph Giliberti via vcf-midatlantic Sent: Wednesday, January 12, 2022 1:47 PM To: vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> Cc: Joseph Giliberti <kd2dhp@gmail.com> Subject: [vcf-midatlantic] Memories of 1977 Greetings! I'm still in planning stages for my homebrew computer and one of my goals is to keep it period appropriate. Part of that is not using any parts or technologies introduced later than 1977. I want my computer to have at least 32k of SRAM. So, by the end of 1977, what was the densest chip commonly available which I won't have to go bonkers trying to locate? Thanks Joe Giliberti -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

Hm, great question. I had to do a bit of searching, but there is an article in the NY Times from January 1977 referencing the newly-introduced MOSTEK 16kx1 RAM with the same pinout as the 4k version. 1kx1, 1kx4, and 4kx1 organizations were around. Looking at CompuPro boards, the EconoRam VII manual I have is dated 3/79 and was 24kx8 using 4k chips. The higher-density RAM16 (using 2kx8 24-pin SRAMs) was dated 1982, so too late, but that gives you some fenceposts. The EconoRam II (8K) used 2102L chips and the manual was dated 1977. The EconoRam IV says 1978 and that used 4kx1 chips (MM5257). Rich -- Rich Cini http://cini.classiccmp.org http://altair32.classiccmp.org <http://www.classiccmp.org/altair32> On 1/12/22, 1:47 PM, "vcf-midatlantic on behalf of Joseph Giliberti via vcf-midatlantic" <vcf-midatlantic-bounces@lists.vcfed.org on behalf of vcf-midatlantic@lists.vcfed.org> wrote: Greetings! I'm still in planning stages for my homebrew computer and one of my goals is to keep it period appropriate. Part of that is not using any parts or technologies introduced later than 1977. I want my computer to have at least 32k of SRAM. So, by the end of 1977, what was the densest chip commonly available which I won't have to go bonkers trying to locate? Thanks Joe Giliberti

Hi Joe, In addition to the 2114 (1k x 4) and the SEMI4200 (4k x 1) that Bill & Jonathan mentioned, there was also 4044 type RAM (4k x 1) in a .3” wide 18pin DIP. I know Dennis Dupre of Electronic Control Technology (ECT) used them in his 16k RAM board dated 1977. The Digital Research Computers 16k board also used the 2114s. I only mention these as I have owned both of these boards. It looks like the pin compatible 2147 (4K x 1) was also released in 1977. The largest RAM boards using these chips I have seen using these chips is 32k such as the CompuPro RAM20 (1981) or the Industrial Micro Systems (IMS) 32k board (1978). There may be others but these came to mind as I have owned both of them. These boards are obviously post 1977 although the RAM chips themselves are not. Best of luck with your design, Jeff Galinat On Wed, Jan 12, 2022 at 11:47 AM Joseph Giliberti via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

Greetings! I'm still in planning stages for my homebrew computer and one of my goals is to keep it period appropriate. Part of that is not using any parts or technologies introduced later than 1977.

I want my computer to have at least 32k of SRAM. So, by the end of 1977, what was the densest chip commonly available which I won't have to go bonkers trying to locate?

Thanks Joe Giliberti