Power Supply

Model 4/4D/4P Power Supply

Jay Newirth (of newSOFT) is selling a Model 4 power supply using modern power supply components while retaining the use of the existing wiring inside the various Model 4 computers.

This revision works for all Model 4’s including the 4P, and has power for both a FreHD and a GoTek.

For more information contact Jay either at JAYNEWIRTH@VERIZON.NET or visit his website at NewSoft Store.

Video/Keyboard

Matt Boytim is developing a small board which can be used to replace the keyboard and/or monitor of a TRS-80 Model 3 and 4.

The project, which can be found at this GITHUB will permit using a PS2 keyboard and/or a VGA or HDMI monitor.

Matt has advised this is still very much a work in progress.



RAM

The Model 4/4D/4P uses 4164 chips. These are still generally available although you need to be careful of the source. Fake chips (or chips that will fail) are very much a risk, so it is important to source them from someone who has run them through a RAM tester. There are people who sell based on how much they have on hand, and you can always try your luck on eBay.

The following list was compiled by Patrick of Texas Tandy Restorations.

4164

Manufacturer
Model
RAM Type
FUJITSU
MB8264
4164
MOTOROLA
MCM6665B
4164
MOSTEK
MK4564N
4164
NEC
uDP4164
4164
OKIDATA
M3764N
4164
OKIDATA
MSM3764
4164
SAMSUNG
KM4164B
Note: “A” will not work
4164
TANDY/MOTOROLA
8040665
4164
TOSHIBA
TMM4164
4164

4116

FUJITSU
MB8116E
4116
MOTOROLA
MCM4116BP
4116
MOSTEK
MK4116N
4116
TANDY/MOTOROLA
8041016A
4116
TEXAS INSTRUMENTS
TMS4116
4116
NEC
uDP416
4116
AMD
AM9016
4116


Feet

Jay Newirth has discovered that the Everbilt 825 031 Rubber Bumpers are an excellent replacement for the feet on a Model III/4/4D. Jay recommends using washers at the bottom to avoid the screws digging into the feet.