Recent content by ardent-blue

Folks, while idly snuffling about for info on the IBM "Internal Tape Backup Unit" Installation Kit, I was sidetracked by mention of the "Multiple Instance Driver for OS/2 PM 1.3/2.0" by Software 2000. Unfortunately, Software 2000 did not make it to 2000. They show up on the Internet Archive in...

ATI 8514 Ultra page. Set JU1 to enable KM93C46 1K-bit serial EEPROM. Run ATI's INSTALL program to set resolution [Set Power-Up Configuration]. Then you have to F10 [IIRC] to save the adapter configuration to the adapter. The INSTALL program is NOT related to the system programs set and view...

This interests me. Not sure how an intel vs POWER system driver would change things, BUT the reason the ROM swap didn't "take" is that the 4 character POSID is hard coded on the adapter. The POS mechanism is based on very simple logic and happens in a very short time, long before a ROM would load.

When IBM used 0 ohm shunts, they used 000, or at least they resembled SMD resistors. I'm right with you about being confused on what the heck those devices are. Inductors usually are the graphite black little bars. Resistors, usually resemble SMD resistors, color-wise. These off-color...

No idea of the efficacy of IBM's approach with the Bermuda Model 77. This is the solder side [bottom] of the Bermuda planar, showing the capacitors and possible resistor networks... Did IBM use R-C networks to protect the serial ports? This is the component side [top] of the Bermuda planar...

I sprayed WD-40 Specialist "Dry Lube" [30005] on the screws, stuff dries very quickly. Carefully turned the screw CCW until I could feel it "drop" then slowly screwed it in. It advanced smoothly until I hit the seam between the frame and the post. Think the glue squeezed a little bit into the...

"Note: RS232 standard is a protocol of the physical level and does not define the transmission speed of all related devices." Shouldn't ignore it, but rightly understand it as a relic of when it was issued [in conjunction with UARTs similar to NS164550]... Better yet, look at the typical L-H...

Found a snippet that supports faster speed [sort of] "Note: RS232 standard is a protocol of the physical level and does not define the transmission speed of all related devices. Transport protocols vary based on devices used. " Even more... Application Note 83 Fundamentals of RS–232 Serial...

We are now approaching the moment of truth. I reattached two snapped off plastic posts on my HP 6100c ScanJet. My hesitation has to do with the break point. Both posts twisted off from the frame right at the juncture of the base of the cylinder and the frame. I dabbed a bit of JB PlasticWeld...

This 7515x experience has forced me to re-think the I/O ASIC functionality. I have NEVER considered the hardware level serial port, I just shook the rubber chicken and chanted the Holy Binaric Hymns... BUT, we have empirical evidence. Most significant, the 7515x combo on the 8560 and 8580...

Model 80 (8580) Serial Port Schematics look at page 7 It shows that all signals to and from the UART go through the 7515x combo. Ooohhh... The pinout on the schematics does not seem to fully match the HITR Serial Port Controller (48 pages) The Type 1 and Type 3 both use the 7515x combo...

I have rarely used a serial mouse on a PS/2... Never made sense, why take up a serial port [IRQ and I/O] if you don't have to?

So, if I grok this gender-bender action, the 75150/75154 takes any TTL activity... but why do both the ASIC serial port [Bipolar] and the 7515x [TTL] use the same pins? Houston, we have a problem... the PS/55 Model 5560 is based on the Model 90 [but the 5560 is more advanced :( ]. The 5560 uses...

Confusing. Either an output short on the 75150, or possibly a [big] reverse voltage on the output pins? Though the reverse voltage would have to be pretty chunky to force it's way into an output gate... I'm desperate, but not serious...

I'm not trying to put up a blizzard of BS, what is a "Low-Impedance Voltage"? The only rail to rail I know of is +12Vdc to -12Vdc. So, the voltage is within the limits, but the Amperage could certainly be excessive...