TweetFollow Us on Twitter

Nubus Slots
Volume Number:6
Issue Number:4
Column Tag:XCMD Corner

Related Info: Slot Manager Resource Manager

Exploring NuBus Slots

By Donald Koscheka, Ernst & Young, MacTutor Contributing Editor

Getting on the NuBus

One of the more salient differences between a personal computer and a mini computer is the bus architecture that is used to pipe data between the processor and its peripherals. Minicomputer designers expend great amounts of energy trying to optimize the system’s bus for throughput and flexibility. Personal computer designers seem to be willing to trade bandwidth for cost and “plug compatibility”. The Macintosh II clearly falls into this latter category. The choice of NuBus could only have been made on economic grounds; technologically it is one of the least inspiring choices possible as is evidenced by the use of byte lanes to correct the fact that NuBus is optimized for intel 808x processors.

While I’m underwhelmed with the choice of NuBus, I have to admit that it’s well documented in yet another outstanding technical reference piece available from Apple, Designing Cards and Drivers for Macintosh II and Macintosh SE (Addison Wesley).

A friend of mine asked if I could put together an XCMD that would return the names of all the NuBus cards plugged into the slots on a Macintosh II. I thought this a reasonable request so I plunged into the Slot Manager documentation in IM Volume V to figure out how to assemble such an XCMD. Like the rest of Inside Macintosh, the Slot Manager is a reference piece; it does a good job of documenting the calls to the slot manager but doesn’t go into a lot of depth on how to use these calls.

I called my friend to tell him that I thought the problem was solvable but that the documentation just didn’t lead to a quick solution. He suggested that I scan “Phil and Dave’s Excellent CD” for some examples on how to use the slot manager. Well the only thing I was able to turn up was a hastily written little application called “getsinfo”. To my chagrin, I couldn’t find any source code to this example so I took out MacNosy and began disassembling the code. Supplementing the information gleaned from MacNosy with some careful TMON walk throughs of the application , I pieced together enough information to write the XCMD.

Listing 1 presents an xcmd that returns a Hypercard list of each card plugged into the slots on a Macintosh II. If no card is plugged into a particular slot, it returns a “Empty Slot”. The information presented here augments what I’ve learned by reading the available documentation and by disassembling some code. Although the code in listing 1 works, it may not be complete or bulletproof so make sure that you use it as a point of embarkation. If you intend to explore NuBus further, I suggest that you get both Inside Macintosh, Volume V and Designing Cards and Drivers. I will be happy to publish any corrections or enhancements to this code if anyone feels inclined to take it out for a spin.

Talking to the Slots

Understanding this code requires a quick refresher course in I/O addressing on the Macintosh. The traditional Macintosh II memory map is depicted in Figure 1. Note that the NuBus cards are addressed just as if they were memory chips located between $90 000 and $EF FFFF. Each slot has up to one megabyte of address space assigned to it. Slot memory starts at location $90 0000 (above the ROM) so the six slots are number from $9-$E rather than from from 1 to 6 as might be expected. When making calls to the slot manager that require a slot number, you’ll want to make sure that the number falls between $9 and $E. Although the Mac II is assigned to slot 0, accessing its memory space will generate a bus error (its memory is assigned from $F0 0000 to the top of memory).

These rules change for 32 bit addressing but the 24-bit mode suffices for illustration.

FIGURE 1. Mac II Memory Model (24 bit addresses )

This memory map goes a long way towards explaining why slots are number starting at 9 rather than at 0 or 1. This doesn’t imply that the slots below 9 are reserved by Apple but rather that slots are numbered to correspond with where they reside in memory.

Communication with the slot manager takes place via a record called the SpBlock (think of it as a parameter block for slots). This “slot block” contains fields that are filled in as needed for a given call (See IM V-439 for more details on the slot block). Typically, you need to supply the slot number in the spSlot field and a slot list identification number in spID. Results are returned in the appropriate field or in the spResult field as needed.

Each NuBus card has associated with it a block of firmware called the declaration ROM. This area of card memory is used to store information that is needed by the card. The declaration ROM is organized into slot resources which act like resources in the Macintosh resource manager (they are related but are not interchangeable). Each sResource has a type and a name. For our purposes, we don’t need to concern ourselves with the exact structure of each sResources. We do need to figure out how to find the card name within the card’s declaration ROM.

Before querying a card in slot x for its name, it’s a good idea to check to see that slot x has a card installed in the first place. In listing 1, this is accomplished using the call to SReadInfo. We pass this call the slot number and the address of an sInfoRecord. Poll the siInitStatusA field of this record to determine whether the card is initialized. If the card is installed and initialized, this field will be set to 0 otherwise it will contain an error message describing why the card couldn’t be initialized. If the slot is empty , siInitStatusA will be set to -300, (smEmptySlot). In our slot loop, we ignore slots that are not installed and set the appropriate entry in the slot name list to “empty slot”.

If the slot is initialized, then we get the spID of the first sResource on the card with the call to sNextTypesRsrc. Now I determined this by disassembling the getsinfo application but it seems to me that sNextRsrc might have been just as useful. Since cards can have multiple functions, they can also have multiple resources. To get the name of each “sub device” you will probably need to walk through the sResource list, thus the call to sNextTypesRsrc.

All I’m really interested in is the spID returned by sNextTypesRsrc. Once gotten, I pass this id to sReadDrvrName to get the name of the driver that handles this card (it seems reasonable to associate the name of the card with the name of the driver that codes for it). This is accomplished with a call to sReadDrvrName although getsinfo appears to take another tack preferring to use SGetCString to extract the card name via a slightly more convoluted scheme. The problem with sGetDrvrName is that it returns the card name as a pascal string preceded by a “.” so that this name can be passed directly to openDriver. No big deal, I simply convert the string back to a “C” string and ignore the first character as it was added to the string anyway.

SlotInfo.c loops for as many slots as it can get information about in the call to SReadInfo. I chose this approach rather than using a for loop (0x09..0x0E) because not all Mac II’s have six slots. Thus slotinfo returns an entry for each slot in the physical machine regardless of whether the slot holds a card or not.

The results of this investigation were interesting. For example, the Apple video card is named the “Toby Frame Buffer” no doubt in honor of its inventor, Toby Frame Buffer. This name may not be too meaningful to the average user so my Hypercard handler for this XCMD converts it to “Apple Video Card”.

Conclusion

At any rate, this is a starting point for anyone that needs to explore programming for NuBus. I hope that the information is mostly correct, but if I’ve made any errors, please be kind enough to pass on the corrections to this magazine so that we can all expand our knowledge of this area.

Ther’s lots of things that you can do once armed with this information such as poll choice locations on the cards, return card status information and, of course, provide a software mechanism for telling the user what’s got under the hood so people don’t have to go around popping their tops every time they want to find out how their Macs are configured.

/****************************************/
/* File: SlotInfo.c*/
/* */
/* Returns a hypercard compatible list */
/* of the names of the cards in each of*/
/* the nuBus slots.*/
/****************************************/

#define UsingHypercard

#include<MacTypes.h>
#include<OSUtil.h>
#include<MemoryMgr.h>
#include<pascal.h>
#include<string.h>
#include “HyperXCmd.h”
#include<HyperUtils.h>
/* obtained from back issues of MacTutor */
#include<SlotMgr.h>

#define SLOT1  0x09

pascal void main( paramPtr )
 XCmdBlockPtr  paramPtr;
{
 short  slotnum  = SLOT1;
 OSErr  err;
 Handle SlotList = NewHandle( 0L );
 short  sResIndex;
 SpBlockslotblok;
 SInfoRecordslotinfo;
 char   slotName[256];
 
 /*** Loop until no more slots found ***/
 
 while( 1 ){
 slotblok.spSlot = slotnum;
 slotblok.spResult = (long)&slotinfo;
 
 if( (err = SReadInfo( &slotblok ) ) == noErr ){
 if( slotinfo.siInitStatusA == 0 ){
 /*** have a card in this slot ***/
 sResIndex = 0;
 
 slotblok.spSlot = slotnum;
 slotblok.spID = sResIndex;
 
 slotblok.spTBMask = 3;
 slotblok.spCategory = 1;
 slotblok.spCType= 0;
 slotblok.spDrvrHW = 0;
 slotblok.spDrvrSW = 0;
 slotblok.spHwDev= 0;
 slotblok.spExtDev = 0;
 err = SNextTypesRsrc( &slotblok );
 
 slotblok.spResult = (long)&slotName;
 
 DebugStr(“\p read name”);
 err = SReadDrvrName( &slotblok );
 
 if( !err ){
 PtoCstr( (char *)&slotName );
 CopyStrToHandle( (char *)&(slotName[1]), SlotList );
 }
 
 AppendCharToHandle( SlotList, ‘\r’ );

 }
 else
 pStrToField( “\pEmpty Slot”, ‘\r’, SlotList );
 
 slotnum++;
 }
 else
 break;
 }
 AppendCharToHandle( SlotList, ‘\0’ );
 paramPtr->returnValue = SlotList;
}

Listing 1. SlotInfo.c XCMD

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Six fantastic ways to spend National Vid...
As if anyone needed an excuse to play games today, I am about to give you one: it is National Video Games Day. A day for us to play games, like we no doubt do every day. Let’s not look a gift horse in the mouth. Instead, feast your eyes on this... | Read more »
Old School RuneScape players turn out in...
The sheer leap in technological advancements in our lifetime has been mind-blowing. We went from Commodore 64s to VR glasses in what feels like a heartbeat, but more importantly, the internet. It can be a dark mess, but it also brought hundreds of... | Read more »
Today's Best Mobile Game Discounts...
Every day, we pick out a curated list of the best mobile discounts on the App Store and post them here. This list won't be comprehensive, but it every game on it is recommended. Feel free to check out the coverage we did on them in the links below... | Read more »
Nintendo and The Pokémon Company's...
Unless you have been living under a rock, you know that Nintendo has been locked in an epic battle with Pocketpair, creator of the obvious Pokémon rip-off Palworld. Nintendo often resorts to legal retaliation at the drop of a hat, but it seems this... | Read more »
Apple exclusive mobile games don’t make...
If you are a gamer on phones, no doubt you have been as distressed as I am on one huge sticking point: exclusivity. For years, Xbox and PlayStation have done battle, and before this was the Sega Genesis and the Nintendo NES. On console, it makes... | Read more »
Regionally exclusive events make no sens...
Last week, over on our sister site AppSpy, I babbled excitedly about the Pokémon GO Safari Days event. You can get nine Eevees with an explorer hat per day. Or, can you? Specifically, you, reader. Do you have the time or funds to possibly fly for... | Read more »
As Jon Bellamy defends his choice to can...
Back in March, Jagex announced the appointment of a new CEO, Jon Bellamy. Mr Bellamy then decided to almost immediately paint a huge target on his back by cancelling the Runescapes Pride event. This led to widespread condemnation about his perceived... | Read more »
Marvel Contest of Champions adds two mor...
When I saw the latest two Marvel Contest of Champions characters, I scoffed. Mr Knight and Silver Samurai, thought I, they are running out of good choices. Then I realised no, I was being far too cynical. This is one of the things that games do best... | Read more »
Grass is green, and water is wet: Pokémo...
It must be a day that ends in Y, because Pokémon Trading Card Game Pocket has kicked off its Zoroark Drop Event. Here you can get a promo version of another card, and look forward to the next Wonder Pick Event and the next Mass Outbreak that will be... | Read more »
Enter the Gungeon review
It took me a minute to get around to reviewing this game for a couple of very good reasons. The first is that Enter the Gungeon's style of roguelike bullet-hell action is teetering on the edge of being straight-up malicious, which made getting... | Read more »

Price Scanner via MacPrices.net

Take $150 off every Apple 11-inch M3 iPad Air
Amazon is offering a $150 discount on 11-inch M3 WiFi iPad Airs right now. Shipping is free: – 11″ 128GB M3 WiFi iPad Air: $449, $150 off – 11″ 256GB M3 WiFi iPad Air: $549, $150 off – 11″ 512GB M3... Read more
Apple iPad minis back on sale for $100 off MS...
Amazon is offering $100 discounts (up to 20% off) on Apple’s newest 2024 WiFi iPad minis, each with free shipping. These are the lowest prices available for new minis among the Apple retailers we... Read more
Apple’s 16-inch M4 Max MacBook Pros are on sa...
Amazon has 16-inch M4 Max MacBook Pros (Silver and Black colors) on sale for up to $410 off Apple’s MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather than a third-party... Read more
Red Pocket Mobile is offering a $150 rebate o...
Red Pocket Mobile has new Apple iPhone 17’s on sale for $150 off MSRP when you switch and open up a new line of service. Red Pocket Mobile is a nationwide MVNO using all the major wireless carrier... Read more
Switch to Verizon, and get any iPhone 16 for...
With yesterday’s introduction of the new iPhone 17 models, Verizon responded by running “on us” promos across much of the iPhone 16 lineup: iPhone 16 and 16 Plus show as $0/mo for 36 months with bill... Read more
Here is a summary of the new features in Appl...
Apple’s September 2025 event introduced major updates across its most popular product lines, focusing on health, performance, and design breakthroughs. The AirPods Pro 3 now feature best-in-class... Read more
Apple’s Smartphone Lineup Could Use A Touch o...
COMMENTARY – Whatever happened to the old adage, “less is more”? Apple’s smartphone lineup. — which is due for its annual refresh either this month or next (possibly at an Apple Event on September 9... Read more
Take $50 off every 11th-generation A16 WiFi i...
Amazon has Apple’s 11th-generation A16 WiFi iPads in stock on sale for $50 off MSRP right now. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-generation 256GB... Read more
Sunday Sale: 14-inch M4 MacBook Pros for up t...
Don’t pay full price! Amazon has Apple’s 14-inch M4 MacBook Pros (Silver and Black colors) on sale for up to $220 off MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather... Read more
Mac mini with M4 Pro CPU back on sale for $12...
B&H Photo has Apple’s Mac mini with the M4 Pro CPU back on sale for $1259, $140 off MSRP. B&H offers free 1-2 day shipping to most US addresses: – Mac mini M4 Pro CPU (24GB/512GB): $1259, $... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.