[Simh] Watch

[Mark Pizzolato]

File protection problems might be a problem, and that is why I asked for the output produced when using his configuration file.  If the file can’t be opened for write there will be an error message and the behavior he’s seeing will be expected.

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Kevin Handy
Sent: Monday, April 11, 2016 12:37 PM
To: Bob Supnik <bob at supnik.org>
Cc: simh at trailing-edge.com
Subject: Re: [Simh] Watch

His nvr file is in /opt/???. Could it be caused by some file protection problems? If the nvr isn't available because of protections, shouldn't it print an error message? Does the file even exist on his system?

On Mon, Apr 11, 2016 at 11:50 AM, Bob Supnik <bob at supnik.org<mailto:bob at supnik.org>> wrote:
Sigh... just looked through ka630_* modules.

Anyway, the byte access/word addressing is in the spec. So the code is allowing writes to bytes that don't exist. Further, it is trying to deal with lengths other than byte or word, and the access and control paths don't exist in the hardware.

VMS uses strictly byte reads and writes to access the watch registers. I don't know what the console ROM might be doing; sources are not available.

/Bob

/* NVR: non-volatile RAM - stored in a buffered file */

int32 nvr_rd (int32 pa)
{
int32 rg = (pa - NVRBASE) & ~01;      /* force even; ignore odd bytes */
int32 result;

if (rg < 14)                                             /* watch chip */
    result = wtc_rd (pa);
else
   result = nvr[rg];

sim_debug (DBG_REG, &nvr_dev, "nvr_rd(pa=0x%X) returns: 0x%X\n", pa, result);

return result;
}

void nvr_wr (int32 pa, int32 val, int32 lnt)
{
int32 rg = (pa - NVRBASE) & ~01;

if (rg < 14)                                             /* watch chip */
    wtc_wr (pa, val, lnt);
else
    nvr[rg] = (uint8) val;

//  sim_debug (DBG_REG, &nvr_dev, "nvr_wr(pa=0x%X,val=0x%04X,lnt=%d) nvr[%02X] was %04X now %04X\n", pa, val, lnt, rg, orig_nvr, nvr[rg] | (nvr[rg+1] << 8));
    }
}

/* NVR examine */

t_stat nvr_ex (t_value *vptr, t_addr exta, UNIT *uptr, int32 sw)
{
uint32 addr = (uint32) exta;

if ((vptr == NULL) || (addr & 01))
    return SCPE_ARG;
if (addr >= NVRBASE+NVRASIZE)
    return SCPE_NXM;
*vptr = nvr[addr];
return SCPE_OK;
}

/* NVR deposit */

t_stat nvr_dep (t_value val, t_addr exta, UNIT *uptr, int32 sw)
{
uint32 addr = (uint32) exta;

if (addr & 01)
    return SCPE_ARG;
if (addr >= NVRBASE+NVRASIZE)
    return SCPE_NXM;
nvr[addr] = (uint8) val;
return SCPE_OK;
}

Note also that the specification of NVR as "4, 16, 32" should be "2, 16, 16". It's a byte-wide memory, but because odd addresses don't work, it has to be specified this way for save/restore.

/Bob

On 4/11/2016 12:00 PM, simh-request at trailing-edge.com<mailto:simh-request at trailing-edge.com> wrote:

------------------------------

Message: 2
Date: Mon, 11 Apr 2016 08:51:08 -0700
From: Mark Pizzolato<Mark at infocomm.com<mailto:Mark at infocomm.com>>
To:"simh at trailing-edge.com<mailto:simh at trailing-edge.com>"  <simh at trailing-edge.com<mailto:simh at trailing-edge.com>>
Subject: Re: [Simh] MicroVAX II time
Message-ID:
        <03006E3FC39B5A48AB9DBCCC101090A82DD620F171 at REDROOF2.alohasunset.com<mailto:03006E3FC39B5A48AB9DBCCC101090A82DD620F171 at REDROOF2.alohasunset.com>>
Content-Type: text/plain; charset="utf-8"

Actually, the watch chip is implemented it is implemented as a separate module
and DEVICE in VAX/vax_watch.c.

The nvr initializes the valid bit in the watch check when the NVR is attached and
clears it when NVR is detached.

Well, I didn’t check the details about 16bit or byte access, but the watch chip
works correctly for me if I use Wilm's config and point it at my generic test disk.
I get prompted for time IF I don't attach the NVR and don't if I do.

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