Smonson's slow H4 build

[Smonson]

I just got my PCB on Thursday and I must say it's very exciting! The quality of these boards is incredible.

I mentioned "slow" in the subject because I don't have most of the stuff I'm going to need to assemble my board, and I'm not even ready to begin.

Unlike most of you guys, I've got a DIP64 HC CPU (16MHz) which I'm hoping can be installed in one of the expansion sockets, instead of a PLCC CPU. My donor chipsets are PLCCs. The SIMM socket price is ...not ideal. I think I'm going to chuck half a meg of DRAM on a veroboard to plug it into the falcon RAM socket instead of giving money to Big-SIMM-Socket, those corrupt bastards.

I don't think I'm going to bother installing some of the non-essential sockets like the cartridge port. Too lazy to desolder it!

[Icky]

:welcomewave: to the H4 party @Smonson

CPU in one of the expansion sockets should be fine and an interesting test for the board.

Looking forward to seeing your HDMI board on the H4 :)

[Smonson]

Now that everyone's finished their boards, it's time for me to start:

h4-1.jpg

I got all the SMTs on there.

With the benefit of everyone else's hindsight, I cut three tracks underneath the video DAC before soldering it in.

2020-01-11.jpg

[Icky]

Now that everyone's finished their boards, it's time for me to start:

I got all the SMTs on there.

With the benefit of everyone else's hindsight, I cut three tracks underneath the video DAC before soldering it in.

Nice! - This is partly why I haven't built the second board yet as doing these neater fixes with hindsight as you say makes for a neater board.

I shall probably do the same when I build the second one.

[PhilC]

That does look like a good idea. Unfortunately I'd soldered two of my boards at the same time with the SMT stuff

[Smonson]

Quick question, what is the ROM part? Does the H4 use a "44-pin JLCC JEDEC" compatible pinout?

[PaulJ]

Quick question, what is the ROM part? Does the H4 use a "44-pin JLCC JEDEC" compatible pinout?

I'm using AT27C4096-55JU-T Mouser# 579-AT27C4096-55JU-T

[Smonson]

Thanks @PaulJ. Gosh they're not cheap for a OTP, are they :shock:

[kodak80]

@Smonson I have used the OTP ones but have also used HN27C4096ACC-10 chips which seem to work fine on stock H4.
https://www.ebay.com.au/itm/1pcs-HN27C4 ... 2103003184

[Smonson]

Thanks for that @kodak80, that's much more like what I expected for an old-style EEPROM.

I never cease to be amazed that you can buy 32GB of flash for $10 and yet a chip with less than a meg on it can be the same price or more.