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JAQ's Blog - Electronics, Microcontrollers, DEC Minicomputers, Raspberry Pi, Airplanes and other stuff....
Total: 21 results found.
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Replacing 2708 EPROM with 28C16 EEPROM
Restoring vintage computers is sure to mean dealing with old EPROMs. Many restorers have a modern EPROM programmer (i.e it was cheap, made in China and I got it on
) or two but there ...
MS11-JP MOS Memory SN#1958348/78
... (E114). I could see activity on the input (pins 9,10,12 and 13) but no activity on output (pin 8). Replacing E114 with a "new" 7440 sourced from
(with what appears to be a 1973 date ...
Kaypro 4/83 Floppy Disk Woes.....
... KayPlus ROM worked but there were a few odd behaviours running some CP/M applications that needed further investigation. In May 2014 a Kaypro II was purchased from
by phorgen on the Vintage Computer ...
TRS80 Model 4P FreHD Installation
... out at the front of the chassis (but inside the plastic case) before it can get into the drive bay. An SD Card extender (available on
) was used to make the SD Card accessible outside the Model ...
TRS80 Model 4 Internal FreHD Install
... PCB and the metal chassis frame. The cable comes out at the top of the Model 4 chassis and then attaches to the connector on the FreHD. An SD Card extender (available on
) was used ...
DL11-W SN#1014374 Repair
... with a logic probe shows that the values displayed on the front panel did match the data out pins on the M5303 UART suggesting a fault with the UART. The M5303 UART is still available from some
Kaypro / FreHD Adaptor - Part 2
... pin header problem was solved using headers from
and offsetting the header that connects to the Kaypro PCB socket from the sockets on the shim where the Z80 and 28C256 EEPROM are installed. ...
TRS80 Model 1 Fixup - Part 3
... afterwards that this behavior would only occur with certain WD1771 chips. I have two different types... an original RS part that I got from Ian and some later "1982" NOS WD1771's that I got on
. Only ...
TRS80 Model 1 Fixup - Part 2
... anyone who finds a parts donor Expansion Interface board and wants to get it going, as of 2013 the WD-1771 floppy controllers are still available on
as are the 4116 dynamic RAM chips. Best ...
TRS80 Model 4 128K Upgrade - Part 2
... and no problems reported. The parts were ordered on
from electron-bg. I would definitely order from this vendor again. ...
TRS80 Model 4 128K Upgrade
... Zealand single board Z80 computer from a company called Computer Specialists so I borrowed the 8 4864 memory chips to test the upgrade. If it worked I would hunt
for some chips. 4864 ...
TRS80 Model 4 Rebuild - Part 4
... searching for a suitable external drive case.... and Trade Me (the New Zealand equivilent of
) turned up 70GB DLT drives for less than $10. The DLT drive occupies a full height ...
Using eBay TTL Serial/USB Interface Modules
With most computers no longer having a serial port, a TTL Serial / USB interface is required for many microcontroller projects. I have had good results with the low cost
modules based on ...
Home Built Z80 CP/M Computer - Part 3
... The end result looks very smart. The two serial interfaces use CP2102 USB/TTL Serial interface adaptors purchased on
for a couple of dollars. They work well in this application easily ...
Home Built Z80 CP/M Computer - Part 2
... Compact Flash to IDE Adaptor on
(approx US$ 2). I have been testing the board with 2 x MAX3232 based TTL to RS232 converter boards. Replacing these with CP2102 based TTL to USB Serial ...
CAT Interface for eBay AD9850 DDS Modules - Part 2
After changing from using the Yaesu FT-817 protocol I picked the ICOM IC-725 as a reference having never seen one. It seemed fairly representative of the use case for the DDS module as a generic ...
CAT Interface for eBay AD9850 DDS Modules
I converted the WB2V/AA0ED/AA0ZZ PIC 16F84 code for controlling the AD9850 to it runs on the PIC 16F628. The 16F628 is a lot cheaper (especially on
in lots of 10), has an internal ooscillator, ...
eBay AD9850 Module Test Board
Test board for the cheap
DDS modules. The board is based on a design by WB2V with software enhancements by AA0ED and AA0ZZ. The cheap AD9850 DDS modules currently available on
eBay AD9850 Module Pinout
The cheap AD9850 DDS modules currently available on
are a great starting point for a signal generator project but are a little short on documentation. The pinout and relationship to ...
Thoughts on the Puxing PX888
... a try. I looked at various online vendors and
sellers and decided to go with www.asiaradiosales.com - primarily based on the fact that their website looked fairly professional. ...
PDP8 SBC6120 FP6120
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