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.
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.
In addition, Jay Crutti has designed a full Model 4 keyboard replacement. You can get more information at https://www.jaycrutti.com/hardware-projects/tandy-trs-80-replacement-keyboards.
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.
| 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 |
| Manufacturer | Model | RAM Type |
|---|---|---|
| FUJITSU | MB8116E | 4116 |
| MOTOROLA | MCM4116BP | 4116 |
| MOSTEK | MK4116N | 4116 |
| TANDY/MOTOROLA | 8041016A | 4116 |
| TEXAS INSTRUMENTS | TMS4116 | 4116 |
| NEC | uDP416 | 4116 |
| AMD | AM9016 | 4116 |
Jay Newirth has discovered that the EVERBILT 1001-687-347 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.