Talk:R800

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This page is substantially duplicated by a piece in an external publication. Please do not flag this article as a copyright violation of that source. The citation is in:

"CPU: Webster's Facts and Phrases". Icon Group International. 2008.

"The internal 8-bit ALU of the Z80 was replaced with a new 16-bit ALU." - as far as I know, Z80 has 4 bit (!) ALU not 8, even if it's from the view point of software. Reference: http://www.righto.com/2013/09/the-z-80-has-4-bit-alu-heres-how-it.html — Preceding unsigned comment added by 176.63.84.111 (talk) 09:36, 24 October 2014 (UTC)[reply]

I'm going to rewrite this article, since it has some incorrections. The first one is about R800 being RISC, as we know, RISC stands for Reduced Instruction Set CPU, and the R800 is anything but a reduced instruction CPU! It has even more opcodes than the Z80. Also the shadowing feature from turboR is attributed to the R800, but actually it's a feature of S1990. Going to add some explanation about the refresh.

The wait state could be removed on normal msxes too. The RAM is fast enough for that in a most msx types —Preceding unsigned comment added by 213.46.38.244 (talk) 19:06, 1 May 2008 (UTC)[reply]

Chip foundry[edit]

ASCII certainly didn't had any chip fabrication plant. Who actually built the chips for them? — Preceding unsigned comment added by 177.132.88.187 (talk) 22:47, 9 November 2012 (UTC)[reply]

Comment on article?[edit]

I have removed a section of the article that is as follows:

Issue detected: The information above about Z80 cycles is not correct. Instruction fetch starts with MREQ signal going active after maximum 85ns delay to the falling edge of the first clock cycle. At the second clock cycle's rising edge DRAMs are fed with row address with RAS going active. On the second clock cycle's falling edge DRAMs are fed with column address and CAS is activated, and Z80 samples WAIT signal activated by the M1 wait state circuit, which extends instruction fetch cycle be one clock cycle. Refresh does not have two parts. Refresh is performed by RAS-only technique, which requires RAS signal to go active for Tras (min 120ns for 4164-120) on the next positive clock edge after both MREQ and RFSH activated. As such DRAM chips require meeting specific timing on RAS activity and RAS precharge, and rising edge of the clock to activate RAS line, two clock cycles are required to perform proper refresh of DRAM chips. See MSX computer circuit diagrams for proofs.

This seems to be a rant about something incorrect with the article. I am not knowledgeable on the subject of the article and therefore will not and cannot fix it. However, if the original author of this quote has an issue with the correctness of the article, (s)he is encouraged to edit it and make appropriate changes. The section that I removed is simply not helpful. hwalter42 (talk) 00:28, 8 November 2014 (UTC)[reply]