Re: [M100] hardware scrolling patch
Follow up on this- I found that my hardware scroll patch conflicts with TS-DOS! TS-DOS uses HahasiH too, so I will need to move to a non conflicting hidey-hole. I don't think I wrote this up at Bitchin100 - I will do so, and post the fixed code. I am working on rolling this patch out on my M100s along with 5MHz upgrade too. Steve On Fri, Feb 25, 2022 at 6:23 PM Stephen Adolph wrote: > So, I burned a ROM and tried it in my T102 (which is socketed). > Interesting results. > It works. > But, visually it is a bit off. Due to the hardware scrolling, you get > wrap around of lines the moment you program the drivers to scroll. > Expected. > However, sometimes that means you get a flash of characters where there > should be none. > This is a bit annoying. > > So, I think I need to redo the patch to remove this artifact. > It wasn't the "same" on VT for some reason. > > Regardless, I'll work on an improved version. > > >
Re: [M100] 27C256 pin 1 VPP - can it float?
I think that means the old 27C256 in the T102 is a bad idea, without an adapter board or a wire to +5V. On Thu, Mar 10, 2022 at 9:52 PM Brian White wrote: > I always tie it to vcc, with a pullup so that a programmer can still > override it. > > As you saw yourself, every datasheet always says to pin to vcc or lower, > usually preferring vcc. > > I think the harm is just the risk of reaching vpp randomly if left > flapping, so you might corrupt the data. Probably *almost* never happens, > but the datasheet directions implies that there is no equivalent of a > built-in pullup, which means the pin is free to spike even from say, static. > > Seperately, I would always nail down *any* input just on principle, and > especially any control input. > > -- > bkw > > On Thu, Mar 10, 2022, 3:32 PM Mike Stein wrote: > >> Don't know about the 27C256 but experience with 2732s was that with some >> manufacturers you could get away with leaving it to float whereas on others >> you had to explicitly pull it high (which would be my recommendation). >> >> m >> >> On Thu, Mar 10, 2022 at 2:20 PM Stephen Adolph >> wrote: >> >>> Quick one for the crowd. >>> On a 27C256, I have always thought you could ignore Vpp for normal use, >>> and only use it for programming. >>> >>> So, you could plug a 27C256 where the main rom lives in a T102 or T200, >>> or UK M100, or KC-85, or M10. whew. >>> >>> However, when I look at datasheets for 27C256, they all say normal >>> condition on pin 1 is VCC!!! >>> >>> What gives? >>> Is it ok to float pin 1, or really should we be connecting pin 1 to plus >>> 5V? >>> >>> thanks >>> Steve >>> >>
Re: [M100] 27C256 pin 1 VPP - can it float?
I always tie it to vcc, with a pullup so that a programmer can still override it. As you saw yourself, every datasheet always says to pin to vcc or lower, usually preferring vcc. I think the harm is just the risk of reaching vpp randomly if left flapping, so you might corrupt the data. Probably *almost* never happens, but the datasheet directions implies that there is no equivalent of a built-in pullup, which means the pin is free to spike even from say, static. Seperately, I would always nail down *any* input just on principle, and especially any control input. -- bkw On Thu, Mar 10, 2022, 3:32 PM Mike Stein wrote: > Don't know about the 27C256 but experience with 2732s was that with some > manufacturers you could get away with leaving it to float whereas on others > you had to explicitly pull it high (which would be my recommendation). > > m > > On Thu, Mar 10, 2022 at 2:20 PM Stephen Adolph > wrote: > >> Quick one for the crowd. >> On a 27C256, I have always thought you could ignore Vpp for normal use, >> and only use it for programming. >> >> So, you could plug a 27C256 where the main rom lives in a T102 or T200, >> or UK M100, or KC-85, or M10. whew. >> >> However, when I look at datasheets for 27C256, they all say normal >> condition on pin 1 is VCC!!! >> >> What gives? >> Is it ok to float pin 1, or really should we be connecting pin 1 to plus >> 5V? >> >> thanks >> Steve >> >
Re: [M100] 27C256 pin 1 VPP - can it float?
Thanks Mike, I did find one datasheet that said "don't care" but others that specify 5V. Good advice, thanks- On Thu, Mar 10, 2022 at 3:32 PM Mike Stein wrote: > Don't know about the 27C256 but experience with 2732s was that with some > manufacturers you could get away with leaving it to float whereas on others > you had to explicitly pull it high (which would be my recommendation). > > m > > On Thu, Mar 10, 2022 at 2:20 PM Stephen Adolph > wrote: > >> Quick one for the crowd. >> On a 27C256, I have always thought you could ignore Vpp for normal use, >> and only use it for programming. >> >> So, you could plug a 27C256 where the main rom lives in a T102 or T200, >> or UK M100, or KC-85, or M10. whew. >> >> However, when I look at datasheets for 27C256, they all say normal >> condition on pin 1 is VCC!!! >> >> What gives? >> Is it ok to float pin 1, or really should we be connecting pin 1 to plus >> 5V? >> >> thanks >> Steve >> >
Re: [M100] 27C256 pin 1 VPP - can it float?
Don't know about the 27C256 but experience with 2732s was that with some manufacturers you could get away with leaving it to float whereas on others you had to explicitly pull it high (which would be my recommendation). m On Thu, Mar 10, 2022 at 2:20 PM Stephen Adolph wrote: > Quick one for the crowd. > On a 27C256, I have always thought you could ignore Vpp for normal use, > and only use it for programming. > > So, you could plug a 27C256 where the main rom lives in a T102 or T200, or > UK M100, or KC-85, or M10. whew. > > However, when I look at datasheets for 27C256, they all say normal > condition on pin 1 is VCC!!! > > What gives? > Is it ok to float pin 1, or really should we be connecting pin 1 to plus > 5V? > > thanks > Steve >
[M100] 27C256 pin 1 VPP - can it float?
Quick one for the crowd. On a 27C256, I have always thought you could ignore Vpp for normal use, and only use it for programming. So, you could plug a 27C256 where the main rom lives in a T102 or T200, or UK M100, or KC-85, or M10. whew. However, when I look at datasheets for 27C256, they all say normal condition on pin 1 is VCC!!! What gives? Is it ok to float pin 1, or really should we be connecting pin 1 to plus 5V? thanks Steve
