RetroFocus2015
New Member
Hello,
while searching for answers about demultiplexing I found this thread on your site www.electro-tech-online.com/threads/what-is-multiplexing.23266/page-2
I've been gathering parts together to build a computer based on designs in the book 'Build Your Own Z80 Computer' by Steve Ciarcia (1981).
I'm doing this as I want to design my own computer. The designs in the book are educational and although good specs for the 1970's maybe not so good by 1980's standards of just a few years later.
As difficult to find and expensive TTL parts are used in the designs inside the book, the low spec trainer ZAP Computer with it's 2K of RAM and 2k ROM was becoming a bit of a 'white elephant' so I've added to it with the 32k RAM and ROM mentioned in the thread and my Z80 turned out to be an 8Mhz Z84 when it arrived.
My problem is I'm also putting a Texas Instruments SN76489 PSG into the computer and I only have one chip enable line available, derived from A15 on the Z80/Z84.
I was thinking I could enable the sound chip at the same tine as RAM as it wouldn't play sound unless told to, even if enabled.
Is this an idea that would work?
while searching for answers about demultiplexing I found this thread on your site www.electro-tech-online.com/threads/what-is-multiplexing.23266/page-2
I've been gathering parts together to build a computer based on designs in the book 'Build Your Own Z80 Computer' by Steve Ciarcia (1981).
I'm doing this as I want to design my own computer. The designs in the book are educational and although good specs for the 1970's maybe not so good by 1980's standards of just a few years later.
As difficult to find and expensive TTL parts are used in the designs inside the book, the low spec trainer ZAP Computer with it's 2K of RAM and 2k ROM was becoming a bit of a 'white elephant' so I've added to it with the 32k RAM and ROM mentioned in the thread and my Z80 turned out to be an 8Mhz Z84 when it arrived.
My problem is I'm also putting a Texas Instruments SN76489 PSG into the computer and I only have one chip enable line available, derived from A15 on the Z80/Z84.
I was thinking I could enable the sound chip at the same tine as RAM as it wouldn't play sound unless told to, even if enabled.
Is this an idea that would work?
Last edited: