Talk:KS10 - Revision history

Jnc: /* Second UBA also 18-bit? */ See Talk:UNIBUS parity for extended research on this point

2025-02-07T13:01:04Z

‎Second UBA also 18-bit?: See Talk:UNIBUS parity for extended research on this point

Jnc: /* Second UBA also 18-bit? */ No, 16-bit only because everything on it was 16-bit only

2025-02-06T14:42:55Z

‎Second UBA also 18-bit?: No, 16-bit only because everything on it was 16-bit only

Larsbrinkhoff: Second Unibus also 18-bit?

2025-02-06T09:58:36Z

Second Unibus also 18-bit?

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==Second UBA also 18-bit?==

I'm trying to figure out whether the "second" (i.e. not disk) Unibus was also operated in 18-bit mode. I have a vague recollection that only the disk controller needed 18-bit data transfers, but I can't confirm this. I read the technical manual, but it doesn't seem to indicate any difference between the two. [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 10:58, 6 February 2025 (CET)

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	: I haven't checked the documentation/code, but my strong recollection is that the second UNIBUS is operated in 16-bit mode only. For one thing, very few UNIBUS devices can operate in [[UNIBUS parity#18-bit width\|18-bit mode]] - the only ones I know of are the [[RH11 MASSBUS controller]] and the [[RK11 disk controller#RK11-E\|RK11-E]]. (Note that the RH11 also needs MASSBUS devices that can operate in 18-bit mode, to operate in 18-bit mode; the [[TM02 magtape controller]] apparently did not have that capability, because the drives that could connect to it only operated in 8-bit mode - again, I have not checked the prints to be certain.) Which would explain why the TM02 and its RH11 are connected to the second UNIBUS. Everything else on that bus was a 16-bit device. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 15:42, 6 February 2025 (CET)		: I haven't checked the documentation/code, but my strong recollection is that the second UNIBUS is operated in 16-bit mode only. For one thing, very few UNIBUS devices can operate in [[UNIBUS parity#18-bit width\|18-bit mode]] - the only ones I know of are the [[RH11 MASSBUS controller]] and the [[RK11 disk controller#RK11-E\|RK11-E]]. (Note that the RH11 also needs MASSBUS devices that can operate in 18-bit mode, to operate in 18-bit mode; the [[TM02 magtape controller]] apparently did not have that capability, because the drives that could connect to it only operated in 8-bit mode - again, I have not checked the prints to be certain.) Which would explain why the TM02 and its RH11 are connected to the second UNIBUS. Everything else on that bus was a 16-bit device. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 15:42, 6 February 2025 (CET)
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		+	: Note to later readers: see [[Talk:UNIBUS parity]] for extended research on this point. The "drives that could connect to it only operated in 8-bit mode" supposition is 'confused' (as we used to say at MIT); the [[TM03 magtape controller]] could function in 18-bit mode, using 8-bit drives - it just threw away half of every 5th byte on the tape. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 14:00, 7 February 2025 (CET)

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	I'm trying to figure out whether the "second" (i.e. not disk) Unibus was also operated in 18-bit mode. I have a vague recollection that only the disk controller needed 18-bit data transfers, but I can't confirm this. I read the technical manual, but it doesn't seem to indicate any difference between the two. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 10:58, 6 February 2025 (CET)		I'm trying to figure out whether the "second" (i.e. not disk) Unibus was also operated in 18-bit mode. I have a vague recollection that only the disk controller needed 18-bit data transfers, but I can't confirm this. I read the technical manual, but it doesn't seem to indicate any difference between the two. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 10:58, 6 February 2025 (CET)
		+
		+	: I haven't checked the documentation/code, but my strong recollection is that the second UNIBUS is operated in 16-bit mode only. For one thing, very few UNIBUS devices can operate in [[UNIBUS parity#18-bit width\|18-bit mode]] - the only ones I know of are the [[RH11 MASSBUS controller]] and the [[RK11 disk controller#RK11-E\|RK11-E]]. (Note that the RH11 also needs MASSBUS devices that can operate in 18-bit mode, to operate in 18-bit mode; the [[TM02 magtape controller]] apparently did not have that capability, because the drives that could connect to it only operated in 8-bit mode - again, I have not checked the prints to be certain.) Which would explain why the TM02 and its RH11 are connected to the second UNIBUS. Everything else on that bus was a 16-bit device. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 15:42, 6 February 2025 (CET)