14 Apr
2018
14 Apr
'18
4 p.m.
On 04/12/2018 09:55 AM, Toby Thain via cctalk wrote:
On 2018-04-12 7:48 AM, Bill Gunshannon via cctalk
wrote:
Yes, but Chuck was describing the
Univac, where char is a 9-bit type,
and a signed char is 1 sign bit and 8 magnitude bits, giving +/- 255.
I'm familiar with Univac's having worked on the 1100 many moons ago,
But look at the line above my comment:
?"you assume that a char is 8 bits, with a signed char having a range
of +/-255".
An 8 bit signed char has the values -128 to +127, as I stated.? even a 9 bit
signed char would not be +/-255 but -256 to +255.
bill
On 04/12/2018 02:45 AM, Chuck Guzis via cctalk wrote:
> On 04/11/2018 06:38 PM, Chuck Guzis via cctalk wrote:
>> On 04/11/2018 02:48 PM, ben via cctalk wrote:
>>
>>> I have a nice 18 bit cpu here, with only a few hardware bugs.
>>> Hmm would it work better if I change that around ideas.
>>>
>>> Care to point to a nice 18 bit version of unix or C.
>>> BTW The cpu has a frame pointer S but no S++ --S operations
>>> so pushing and popping wild data is not a option.
>> Well, the Univac 1100/2200 series mainframes ran V7 Unix--and they're
>> 36-bit machines, so probably not far from your 18-bitter--and they're
>> ones' complement machines.
>>
>> Univac called it "SX1100", so you have a search term.
> Remarkably, Unisys keeps a lot of old documentation around. Here's the
> reference manual for their "C" on th 1100:
>
> https://public.support.unisys.com/2200/docs/cp14.0/pdf/78310422-011.pdf
>
> Looks pretty much like standard C until you get into the minutiae, such
> as "A character constant is 1 to 4 characters" ...
Apple also used
this extension in their Mac C compilers.
(9 bit
characters and 36 bit ints and 18 bit short ints).
So, it should be pretty straightforward unless you assume that a char is
8 bits, with a signed char having a range of +/-255.
Signed 8 bits would be? -128 to +127.